Prehistoric (23)
http://www.worldheritagesite.org/categories/category24.html

Catalhöyük
Ban Chiang
Bat, Al-Khutm, Al-Ain
Biblical Tells (actually not prehistoric, these cultures were literate)
Bru na Boinne
Choirokoitia
Hal Saflieni
Ibiza
Kakadu (better under rock art)
Kernave
Lenggong
Matobo (better under rock art)
Megalithic Malta
Nasca lines (here I don't understand why Nasca line enters here whereby other prehistoric Precolumbian sites such as Samaipata, Tierradentro, Diquis, Poverty Point and Head-Smashed-In are absent.)
Spiennes
Orkney
Pile dwelling
Sammallahdenmäki
Stonehenge
Tasmanian Wilderness
Tiya
Tsodilo (better at rock art)
Yagul and Mitla

I would also add: Saloum, Rock Island, Kuk, Sarazm.

My selection:

Catalhöyük - largest and best preserved neolithic site
Biblical Tells - for water management
Bru na Boinne - beautiful megalithic constructions
Hal Saflieni - one of the oldest buildings
Matobo/Tsodilo - I don't know which one
Nasca lines - enigmatic, beautiful
Orkney - maybe
Stonehenge - iconic
Kuk - oldest agriculture in Oceania
Saloum - especially large concentration of middens

Prehistoric (23) YES – 6, MAYBE – 5, NO – 8 Not Applic - 4

-Catalhöyük -YES – well preserved dwellings from the earliest periods of man's "settlement"
-Hal Saflieni - YES – But that creates a major problem for Malta's other megalithic site!
-Lenggong - YES – for its record of first of Human dispersal into Asia and then Human occupation over an enormously long period?
-Stonehenge - YES – Iconic etc etc
-Orkney - YES – primarily for Skara Brae with its amazingly "complete" representation of a Neolithic dwelling in a fine setting. But that does create a major problem with Bru na Boinne which is also magnificent!!
-Nasca lines – YES –whatever "category" it is assigned to it has to be included for its iconic status and "Mystery"

Ban Chiang – MAYBE – at most (and I would tend to "NO"). Yes it covers a part of the World not well represented at this period (5th Mill BC SE Asia) – but does it add enough? Lenggong exceeds it in time period.
-Kernave – MAYBE - covers a very long period from 10th mill BCE - but does it "do" any of them particularly well? Lots of sites have evidence of very long occupation. The "Hill Forts" which seem to be the main "claim to fame" may have been present since BCE but the remains seem mainly to be Mediaeval"?
-Bru na Boinne – MAYBE - A very fine site but it faces a lot of competition in this "category". It would have to replace Orkney on the grounds that Stonehenge is "iconically" sacrosanct!
-Megalithic Malta – MAYBE - Really should have been combined with Hal Saflieini and therefore be a "YES". I just don't see how Hal Saflieni can be excluded. Perhaps we just have to include both!!
- Spiennes – MAYBE (just!)- after this year's "adventures" to get to see it I am perhaps too inclined NOT to dismiss it out of hand!! Flint was important and this represents a massive early "industrial" site. Flint could be represented by Atapuerca if that is selected

-Bat, Al-Khutm, Al-Ain – NO – Have visited. More Bronze Age tombs –and in varying condition. They represent an era when this area was significant as a source of metals but, despite trying, I can't convince myself that they are significant enough
-Choirokoitia – NO – Have visited. It is nice but I don't think it adds enough to the other sites from the period
- Ibiza - NO- not for its "Phoenician ruins" (though should it be here either?
- Pile Dwellings - NO - I guess this type of structure has a certain significance in representing the development of habitation and civilisation....But? This site also has the "problem" of having very little to actually see since remains are either under water, have degraded or have been covered up. That lack of visibility shouldn't be a complete killer but has to be taken into account.
-Sammallahdenmäki – NO –We have plenty of other "bronze Age" sites so this one's main claim is its "regional" significance. Not enough in my view
-Tasmanian Wilderness – NO – not for this aspect
-Tiya – NO - have visited - it is just not important enough (and its period is probably not even "pre-historic")
Yagul and Mitla - NO- A strange nomination. Majors on the caves and domestication of Maize but still includes the post-classical Zapotec sites (knowing presumably that these were not really strong enough given all the other similar inscribed sites!). ICOMOS was not impressed and whilst conceding that the early domestication aspect might be a runner recommended REferral

-Biblical Tells - N/A - Have already assessed under Near Eastern Archaeology)
-Kakadu - N/A - better under rock art
-Matobo - N/A - better under rock art
-Tsodilo - N/A - better under rock art

My selection:

Bru na Boinne (maybe)
Hal Saflieni (prehistoric underground)
Megalithic Malta & Gozo (I agree with Assif)
Stonehenge
Catalhoyuk (maybe)

This category is again very hard to choose as many pre historic sites are very important but when visit nothing much to see or really hard to understand. From my experience, I support:
- Stonehenge, very nice site would be good if they let visitor see it more closer!
- Nasca, unique and real wonder.

I select the Pile Dwellings! No, just kidding...

I'd go for:
- Catalhöyük - one of the first, if not the first, human city; even frescoes were identified
- Bru na Boinne - for pre-historic burial traditions mixed with astronomic considerations
- Megalithic Malta - prefer the "outdoor" Maltese temples to the hypogeum
- Nasca lines - unique and iconic
- Orkney - for Skara Brae village
- Stonehenge - well, I guess this one is almost self-evident

My selections

Bru na Boinne - beautiful megalithic constructions
Hal Saflieni - one of the oldest buildings
Nasca lines - enigmatic, beautiful
Stonehenge - iconic
Catalhöyük -well preserved dwellings from the earliest periods of man's "settlement"
Megalithic Temples of Malta ( I like both)

Neolithic Orkney- Maybe (It just surpassed by Stonehenge and Boinne in my case)

Wrapping this one up. Rather clear:

Catalhöyük - well preserved dwellings from the earliest periods of man's "settlement"
Ban Chiang
Bat, Al-Khutm, Al-Ain
Biblical Tells
Bru na Boinne - for pre-historic burial traditions mixed with astronomic considerations
Choirokoitia
Hal Saflieni - one of the oldest buildings
Ibiza
Kakadu
Kernave
Lenggong
Matobo
Megalithic Malta
Nasca lines - for its iconic status and "Mystery"
Spiennes
Orkney - primarily for Skara Brae with its amazingly "complete" representation of a Neolithic dwelling in a fine setting
Pile dwelling
Sammallahdenmäki
Stonehenge - iconic
Tasmanian Wilderness
Tiya
Tsodilo (better at rock art)
Yagul and Mitla