Rock art (24)
http://www.worldheritagesite.org/categories/category62.html

Altamira
Chongoni
Coa Valley/Siega Verde
Cueva de las Manos
Chauvet Pont d'Arc
Gobustan
Kakadu
Kondoa
Maloti/Drakensberg
Matobo
Mongolian Altai
Hail
Alta
Tanum
Valcamonica
Sierra de San Francisco
Bhimbetka
Rock art of the Mediterranean Basin
Serra da Capivara
Tadrart Acacus
Tamgaly
Tassili n'Ajjer
Twyfelfontein
Vezere

Add: Tsodilo

For most of them I just find it too difficult to decide, so their exclusion does not imply a NO.
Some I would support:

Altamira - iconic, yes
Cueva de las Manos - maybe, for the design as well as its remote location in Patagonia.
Chauvet Pont d'Arc - yes, for artistic quality
Kakadu - maybe, to represent aboriginal Australia (although I would rather have Burrup Peninsula (Murujuga))
Alta - yes, for the remote location. It's the northernmost cultural WHS and represents polar culture well.
Valcamonica - at least a maybe for the artistic quality.
Rock art of the Mediterranean Basin - probably a no, Altamira is enough for this area.
Serra da Capivara - yes, for being one of the oldest cultural sites in the Americas and the earliest one of this scale. It also still plays a role in determining the chronology of the first immigration to the Americas.
Vezere - iconic, yes.
Tsodilo - yes, for its current religious role and feminist aspect.

Coincidentally, we discussed the issue of "Rock Art" on the List here a couple of months ago. I did a quick analysis and discovered some 60 WHS which contained Rock Art (graph or glyph). 24 of these were inscribed significantly because of their Rock Art (ie included in the OUV) and around 12 of these even had the "Rock Art" aspect in their name as, in effect, the main reason for their inscription. See http://www.worldheritagesite.org/RockArtWHS1.xls

So, we have a "Gothic Cathedral" situation here! How many to choose and how to differentiate. Age/period, "artistic" merit, geography/culture?
A number of the sites with significant Rock art are (probably?) going to get chosen for other aspects so ,even if we chose none from this category, the propensity of Mankind to express itself in this way would still be represented for our "Little Green Man". This is particularly the case for more "modern" examples where they form part of e.g African Cultural Landscapes. There are 8 African sites listed above and there are others too - e.g Lope.
My inclination is to choose just one of the most "significant" ones under this category and leave the rest to appear under CLs etc. The earliest seem to me to be the most significant - so it has to be Altamira.

My selection:

Vezere: most iconic and well preserved
Grotte Chauvet: maybe, again artistically beautiful but I'd choose Lascaux for my top 200
Altamira: maybe, same as above
Alta: my favorite to represent Scandinavia
Valcamonica: maybe, to represent pile dwellings too
Serra Capivara: same as Assif

YES
Chauvet Pont d'Arc - stunning, most important cave art in Europe
Tsodilo - Louvre of the Desert

MAYBE
Vezere - iconic, but not as old or artistically skilled as Chauvet.
Altamira - a bit older than Chauvet, but not as stunning.

This one needs a summary.

Summary:

Altamira
Chongoni
Coa Valley/Siega Verde
Cueva de las Manos
Chauvet Pont d'Arc
Gobustan
Kakadu
Kondoa
Maloti/Drakensberg
Matobo
Mongolian Altai
Hail
Alta
Tanum
Valcamonica
Sierra de San Francisco
Bhimbetka
Rock art of the Mediterranean Basin
Serra da Capivara
Tadrart Acacus
Tamgaly
Tassili n'Ajjer
Twyfelfontein
Vezere

Add: Tsodilo

We could use some more voices here.

I've visited a number of them, and they're often quite underwhelming when you get there eventually.
Of these, I'd like to put forward Kakadu (great park and the Aboriginal rock art gives it a little extra) and the Bhimbetka Rock Shelters.

From the ones that I haven't visited, I'd like to see a geographical spread. Below my arbitrary choices,
- Northern Africa: Tadrart Acacus or Tassili n'Ajjer? - Tadrart Acacus seems to have "better" paintings
- Southern Africa: Twyfelfontein stands out because they are rock engravings
- Americas: has to be the Cueva de las Manos for its quirkiness and age
- Europe: Altamira Cave for its historic significance

So far, this would upgrade Altamira to bold and Kakadu to cursive.

My selection

Lascaux (vezere)- most remarkable paleolithic cave paintings in the world, from at least 15,000 years ago (not accessible to public)
Chauvet - around 32,000 years old, one of the earliest in whs list
Serra da Capivara- largest concentration of prehistoric sites in the Americas.
Kakadu - unique artwork of the Aboriginals
Bhimbetka - 600 rock shelters (Asian unique rock art)
Tadrart Acacus- Significant for study as paintings reflect the changing environment of the Sahara desert

New summary (also counted half-votes for the maybe's):

Altamira - for its historic significance
Chongoni
Coa Valley/Siega Verde
Cueva de las Manos - for its quirkiness and age
Chauvet Pont d'Arc - artistically beautiful
Gobustan
Kakadu - unique artwork of the Aboriginals
Kondoa
Maloti/Drakensberg
Matobo
Mongolian Altai
Hail
Alta - for the remote location. It's the northernmost cultural WHS and represents polar culture well.
Tanum
Valcamonica
Sierra de San Francisco
Bhimbetka - 600 rock shelters (Asian unique rock art) -
Rock art of the Mediterranean Basin
Serra da Capivara - for being one of the oldest cultural sites in the Americas and the earliest one of this scale.
Tadrart Acacus - Significant for study as paintings reflect the changing environment of the Sahara desert
Tamgaly
Tassili n'Ajjer
Twyfelfontein
Vezere - most iconic and well preserved

Add: Tsodilo