What sort of 'fabulous shots' interest you?
The major temple complexes (Wats) of Bangkok are not easy to photograph as they are very much over-visited by hoards of tourists. It's essentially impossible to get good clean shots at Wat Phra Kaew or Wat Po for example. If you want to shoot temples I would suggest visiting some of the less well known No reason to take a tour of any kind. Public transportation is great, finding your way around is easy. Just carry a card from you hotel. If you get really lost you can take a metered cab home for a few dollars. (I get some of my best shots when I'm lost.)
Bangkok has a very nice new bridge across the Pray Chao River. And there's the Turtle Temple where you can get some great turtle and iguana closeups. (You have to step over them.)
If you want to shoot ruins visit Ayuthaya and Sukhothai. If you want to shoot monkeys visit Lopburi (hundreds roam the street). In general the up-country temples are much easier to photograph. Chiang Mai, Chiang Rai, and Phitsanulok are good places for shooting temples.
Cambodia, of course the temple complexes around Siem Reap. A minimum of three days is needed just to visit the major Wats. Angkor is great, but Bayon with its giant stone faces and Ta Prohm which is still somewhat overrun by the jungle actually provide more photo opportunities.
The river trip between Siem Reap and Battambang is a great opportunity to shoot life along the river (take the slow boat).
Southern China - around Kunming there is the spectacular Dragon's Gate and the Stone Forrest.
(I could go on for a few pages.)
Suggest you go to Trek Earth
. Click on Galleries, then Asia, then Thailand, etc. You will see the work of a large number of different photographers. There will be location info with each picture.
If you have any particular questions feel free to email me.