I took a tour there last year, pretty fun. You pick a good time to go to Thailand, the summer is intolerable. I was there in Jan, very high humidity, could barely stand the heat then. There isn't all that much in Bangkok, there's just the King's palace, a couple of temples, and a lot of shopping.
Make sure you drop by Pataya and see the transvestite theatre shows, there's 2 of them, and they really are very unique.
Sarcasm, the 6th Ponyman of the Apocalypse.
Please do not inquire about Tim, the 5th Ponyman.
Amazing amazing country.....I spent 6 weeks there this year(4 in march and another 2 in July).
You have to get down to the islands. The islands are paradise. You can't beat eating in restaurants on the beach watching the sunsets for $1-2US. Get down to Koh Tao, much nicer than Ko Phangan(where the famous full moon parties are held) IMO.
If you like temples, go to the old capital ayutaya(spelling)(about 2 hours nth of bangkok). We paid our driver $2 US for about 2 hours of tuk tuking around all the sights. Doesnt seem like much, but he was happy, and we gave him a good tip at the end...
If you've never been to SE Asia before, Bangkok will just blow you away. Absolute madness.....Chaos....Heat....Smells....People.....
If you like shopping( i don't..but I managed to like it in Thailand), Chang Mai is good. And if you do a hilltribe trek, be warned there are a few that are quite remote and really good, and a few that a so touristy that you are more likely to meet tribes with cable tv than true hill tribes.