Originally Posted by jiejie

There are many more than 10 "must visit" places in SE Asia. Don't take this personally, but this is a seriously useless question without knowing two things:
1) How long you have to spend. A week? A month? 3 months? SE Asia doesn't look like it takes up much room on the globe, but it is rich in offerings, and some rewarding places take a certain minimum investment in time to make it worth one's while.
2) Your general and specific interests. I can give you 10 must-visit beaches, or 10 must-visit temples, or 10 must-visit girlie bars. Oops, sorry not that last one--other FT'ers will have to help you out there.

I think you get my drift. The usefulness of answers will depend on a more detailed framing of your question. Would also be helpful to know general time of year you plan to visit.