Do you have a tentative wish list for a country you travelled extensively? Here is mine for the US. Some of these sites may even make it into the 2016 update.

United States Tentative Wish List (12 nominations)

Extensions/Transnational Nominations (5)
- Camino Real - Santa Fe (New Mexico) Transnational Extension - Mexico property
- Organ Pipe Cactus National Monument (Arizona) Transnational Extension - Mexico property
- First Peoples Buffalo Jump (Montana) Transnational Extension - Canada property
- The Klondike (Alaska) Transnational Nomination - Canada
- Grand Canyon National Park (Arizona) Re-nomination mixed

New Nominations (7)
- Chicago School of Architecture (Illinois)
- Historic Charleston (South Carolina)
- Colonial Newport (Rhode Island)
- Ancestral Sites of the Diné - Monument Valley & Canyon de Chelly (Navajo Nation/Arizona) mixed
- Sinagua Cultural Landscape (Arizona)
- Sequoia & King's Canyon National Park (California)
- Mojave and Colorado Deserts Biosphere Reserve (California) serial nomination, 5 components - Death Valley/Joshua Tree/Mojave/Santa Rosa and San Jacinto Mountains/Anza-Borrego Desert

I would love to hear other tentative wish lists!

Living in Central Europe, the countries you usually travel extensively are not really underrepresented and also very active on the T-List.

From my country Switzerland) I would like to see the Old Town of Lucerne on the t-list. On Germany's T-List I miss Rothenburg (on the FTWHS list). From the other countries I visit frequently I miss the Corinth Canal in Greece, and Aigues Mortes in near Nimes, France.

From my 2014-2015 trips:

Bulgaria
- historic town of Koprivshtitsa

Czech Republic
- Demänovská Ice Cave

India
- Meenakshi Amman Temple

Italy
- Church of Sant' Andrea and Ospedale del Ceppo, Pistoia

Japan
- Chikurin-ji (Kōchi)

Romania
- Bicaz Gorge

Slovenia
- Predjama Castle

United Kingdom
- York Minster

A fair few of my wishes ended up on the Top 50 missing exercise most notably: Olympic Park Munich, Baikanour Cosmodrome/ Kennedy Space Center, Chicago School architecture

I've been in the USA a lot recently, I know winterkjm has provided a fair few above, but these are some of my additional ideas. Will come back with some other non USA ones later.

USA
-Sites of the Manhattan Project
-Mid-century Modern Architecture of Palm Spring
-Case Study houses of Los Angeles
-Neo-futurist architecture of Eero Saarinen (TWA Terminal at JFK Airport, Gateway Arch, Dulles Airport...)
-Mormon Pioneer Trail - An American Exodus

My list for Germany. The country is already well represented, but still some potential to fill some gaps.

- Olympic Park Munich
- Tempelhof Airport
- TV tower Stuttgart, the first TV tower built from concrete, and in my opinion the most beautiful tower basket
https://en.wikipedia.org/wiki/Fernsehturm_Stuttgart
- Radom Raisting, the first terrestrial radio station in Europe for the communication with satellites, e.g. used for the live transmission of the first moon landing and the Olympic Games in 1972
http://www.radom-raisting.de/?view=article&id=94
- Liebig's Laboratories at Gießen, https://de.wikipedia.org/wiki/Liebig-Museum
- AEG turbine factory by Peter Behrens, https://en.wikipedia.org/wiki/AEG_turbine_factory
- Extension of Zollverein Essen, eg Zeche Zollern, Hansa Cokery, Henrichenburg boat lift, metallurgical plant Duisburg, Gasometer Oberhausen

Not sure about this - France has Pleumeur-Bodou and UK has Goonhilly Down (Unless you don't consider UK to be a part of "Europe"!!) both used for Telstar in 1962 and both are preserved monuments at National level
See
https://en.wikipedia.org/wiki/Goonhilly_Satellite_Earth_Station
and
https://fr.wikipedia.org/wiki/Centre_de_t%C3%A9l%C3%A9communication_par_satellite_de_ Pleumeur-Bodou

I would like to see some intact prisons on Germany's t-list like Berlin-Hohenschoenhausen,Cottbus or Bautzen.

My personal wish list, which does not include sites in the tentative lists (since those are already under consideration). While I have not personally been to many of these sites, they are for the most part iconic, picturesque, naturally/culturally important, especially if sites of questionable OUV such as WWI memorials are already on the list

Antarctica

Bolivia
- Salar de Uyuni

China/Vietnam
- Ban Gioc-Detian Falls

Germany
- Berlin Wall

Greece
- Santorini

Israel/Palestine/Jordan
- Dead Sea

Italy
- Milan Cathedral

India
- Meenakshi Temple

Iraq
- Imam Ali Shrine in Najaf
- Imam Husayn Shrine in Karbala

Ireland
- Cliffs of Moher

Japan
- Ise Grand Shrine

Mexico
- Tulum

Panama
- Panama Canal

Saudi Arabia
- Mecca

Spain
- Guggenheim Museum Bilbao

Turkiye
- Mount Ararat

UK
- Oxford/Cambridge

USA
- National Parks in Utah (Bryce Canyon, Arches, etc)
- Death Valley NP
- Monument Valley
- Niagara Falls

Japan
Tokaido Shinkansen
Ueno Park

Norway
Norsk Folkemuseum (King Oscar II's collection in particular)

UK
Liverpool Albert Dock (Potentially extendable to cover The Three Graces?)
Stockton and Darlington Railway - Locomotion Museum/Skerne Bridge/Head of Steam museum
Tynwald Hill
Works of Charles Lanyon - Belfast Custom House/Botanic Gardens Palm House/Crumlin Road Gaol & Courthouse/Linenhall Library/Queen's University/Sinclair Seaman's Presbyterian Church/St. John's Church/The Abbey

USA
Movie Palaces of Los Angeles

My list for Western US:

- Cascadian Peaks (Baker, Ranier, St. Helens, Adams, Hood, Three Sisters, McLoughlin, Shasta)
- Columbia Gorge
- Griffith Park and Observatory
- Watts Towers
- Movie Palaces of LA
- Catalina Island
- Palm Springs Houses
- Arizona Saguaro Forests
- White Sands
- Monument Valley
- Utah National Parks

I would add to the TWHS (A-M):

Afghanistan: Ai Khanum, Surch Kotal
Argentina: El Palmar NP
Australia: Channel Country, Christmas Island, Coober Pedy, Dryandra Woodlands, Flinders Chase NP, Great Ocean Road (incl. neighbouring NPs), Karijini NP, Lake Hillier, Litchfield NP, Maree Man, Montgomery Reef, Moorrinya NP, Nambung NP, Watarrka NP
Azerbaijan: Neft Deslari
Belgium: Atomium
Bolivia: Altiplano, Kaa-Iya del Gran Chaco NP, Rainbow Mountain, Salar de Uyuni, Yungas Road
Brazil: Chapada Diamantina NP, Encontro das Águas, Fordlandia, Itaipu Dam
Canada: CN Tower, Montréal souterrain, Wapusk NP
Chile: Alberto de Agostini NP, Chuquicamata Open Pit, La Campana NP, Pumalin Park, Valle de la Luna
China: Bird's Nest, Chanthang Nature Reserve, Mount Kailash, Red Beach of Panjin, Shunan Bamboo Forest, Three Pagodas of Dali, Zhangye Danxia
Colombia: Cano Cristales, Paramo de Oceta or Sumapaz NP, Salt Cathedral of Zipaquirá
Costa Rica: Beach of Ostional, National Archeological Park of Guayabo de Turrialba
Cuba: Presidio Modelo
Denmark: Quinngua Forest
Egypt: Hierakonpolis, White Desert
Ethiopia: Danakil Depression
France: Beauvais Cathedral, Bora Bora, Centre Pompidou, Channel Tunnel, Chateau de Vincennes, Devils's Island, La Defense, Monuments des Mortes de Paris, Opera Garnier, Viaduc de Millau
Germany: Berlin Wall (incl. Reichstag/Brandenburg Gate), Hallertau, Hillfort of Otzenhausen, Lüneburg Heath, Nazi Party Rally Grounds, Peasants' War Panorama, Rothenburg ob der Tauber, Tempelhof Airport, Ville Lakes, VW-Factory at Wolfsburg, Wuppertal Suspension Monorail
Greece: Santorini
Guyana: Kaieteur NP
Hungary: Budapest Ghetto and 4 synagogues
Iceland: Blue Lagoon, Skeifararsandur / Black Sand Beaches
India: Edicts of Ashoka (with Pakistan), Backwaters Kerala, Meenakshi Temple, Pandua / Gaur, Statue of Unity, Tea Plantations of Darjeeling & Assam, Victoria Memorial
Indonesia: Bogani Nani Wartabone NP, Kelimutu Coloured Crater Lakes
Iraq: Arch of Ktesiphon, Imam Husayn Shrine in Kerbala
Iran: Tarichane Mosque
Ireland: Clonmacnoise, Killarney NP, The Burren & Aran Islands
Israel/Jordan: Dead Sea
Italy: Capri, Capuchin Catacombs of Palermo, Cathedral of Otranto, Coastal Fortifications of Apulia, Ostia Antica, Staglieno Cemetery, Turin: Mole Antonelliana & Lingotto
Japan: Castles and Imperial Gardens of Kyoto, Historic Onsens (Humans & Monkeys), Ueno-Park
Libya: Great Man Made River
Lithuania: Hill of Crosses
Madagascar: Avenue of the Baobabs
Mauretania: Richat Structure
Mexico: Cascadas de Agua Azul, Cave of the Crystals, El Mirador, Ferrocarril Chihuahua al Pacífico, Great Pyramid of Cholula, La Venta, Sierra de la Laguna Biosphere Reserve
Micronesia: Chuuk Lagoon (Shipwrecks)
Mongolia: Hustai NP
Morocco: Chefchaouen, Ifrane NP
Myanmar: Kyaiktiyo Pagoda

Afghanistan Shrine of Hazrat Ali
Algeria Ahaggar National Park
Antarctica McMurdo Dry Valleys
Bahamas Blue Holes National Park / Dean's Blue Hole
Belgium Atomium
Bolivia Eduardo Avaroa Andean Fauna National Reserve
Brazil Maracana
Canada / United States Niagara Falls
Chile Cabo de Hornos National Park
China Hong Kong, to be determined
China Kailash
China Qomolangma National Nature Preserve
China Shanghai, to be determined
Cyprus / Northern Cyprus Walled Old City (Nicosia)
Egypt Suez Canal
Ethiopia Danakil: Dallol / Erta Ale
France Abbaye de Cluny
France Arc de Triomphe
France Bagne de la Guyane française
France Château de Chantilly
France Cimetière du Père-Lachaise
France Giverny
France Grotte Cosquer / Parc national des Calanques
France Le Mans: Cité Plantagenêt
France Montmartre
France Parc amazonien de Guyane
France Parc national de la Guadeloupe
France Phare du Créac'h
France UNESCO Headquarters
France Viaduc de Garabit
France Vieux-Port de La Rochelle
Germany Berlin Wall / Brandenburg Gate
Germany Nazi Party Rally Grounds
Greece Santorini
India Buddhist monasteries in Ladakh
India Mehrangarh
India North Sentinel Island
Indonesia Bromo Tengger Semeru National Park
Indonesia Kawah Ijen
Indonesia Kelimutu
Mauritania Richat Structure
Mexico Bonampak
Mexico Cave of the Crystals
Mexico Tula
Myanmar Kyaiktiyo Pagoda
North Korea 20th-century architecture in Pyongyang
Panama Panama Canal
Romania Bran Castle
Russia Moscow Metro
Russia Perm-36
Russia Seven Sisters (Moscow)
Rwanda Volcanoes National Park
Saudi Arabia Masjid al-Haram
Slovakia Cachtice Castle
Somaliland Laas Gaal
South Africa Kruger National Park
Spain Campo de Criptana
Spain Las Ventas
Switzerland Matterhorn
Taiwan To be determined
Thailand Wat Phra Kaew
Ukraine Chernobyl
United Kingdom Buckingham Palace / Windsor Castle
United Kingdom Great Glen
United Kingdom Oxbridge
United States Arches National Park
United States Bryce Canyon National Park
United States Crater Lake
United States Devils Tower National Monument
United States Empire State Building
United States Golden Gate Bridge
United States Hoover Dam
United States Los Angeles: Disneyland / Hollywood
United States Meteor Crater
United States Miami Beach Architectural District
United States Monument Valley
United States Mount Rushmore
United States Old French Square of New Orleans
United States Washington (District of Columbia)
Zambia Kasanka National Park

Moreso from travels of people I know and general research than my own travels, I've compiled my wish list for Ukraine. Some of the sites were (and maybe still are?) seriously considered for TWHS status, but most are not from what I can tell.

Cultural:
- Cucuteni–Trypillia Sites (transnational w. Moldova and Romania) [circa 6000–3000 BC]
- Scythian Neapolis (perhaps not very impressive but it is the best-preserved example of a Scythian settlement) [3rd century BC – 3rd century AD)
- Khotyn Fortress [10th–14th centuries]
- Lutsk Castle [14th century]
- Russian Imperial Palaces in Ukraine (e.g., Vorontsov Palace, Livadiia Palace, Masandra Palace, Dulber Palace, Kachanivka Palace, Popov's Manor) [18th–19th centuries]
- Malyi Galagov [1920's–1930's]
- Soviet Workers' Settlements (Sixth Village in Zaporizhzhia, district of the Kharkiv Tractor Plant in Kharkiv) [1930's]
- Khreshchatyk [most buildings from 1940's–1960's; a few from Imperial era survived]

Mixed:
- Chornobyl Exclusion Zone (including not only parts of Chornobyl and Prypiat but also the protected natural area around the cities)
- Kaniv Hills (essentially an extension of the questionable TWHS of Taras Shevchenko Museum and Preserve)

Natural:
- Bug Gard National Nature Park
- Caves of Ternopil Oblast
- Karadag Nature Reserve
- Oleshky Sands National Nature Park
- extension of Danube Delta (the Romanian part of which is a WHS already)

Great thread! I carefully read all your wish lists....got quite a few new ideas thanks to them.

Las Ventas in Spain.......I very much like your wish,jonathanfr
Been there 4x....one of the most wonderful places on earth ....well...
I am aficionado of the corridas