I took an air asia flight to get from bangkok to phuket, it was like $50 at the time and would have otherwise been an insanely long train ride. Only time I've been on a plane without assigned seats.
When I was there it was right after Thaksin came down really hard on drugs. They were literally killing major drug suppliers so a lot of thai people were scared shitless to even buy weed. That being said it still seemed to be around everywhere and I even saw people smoking yaba at the clubs. Just be smart I guess.
If no one warned you already bring some toilet paper, only westernized places will have it when you're there. Though with the weather being so hot I really grew to appreciate a nice cold blast from a bidet.
I was scratching my head a bit and remembered a few places:
Best middle eastern food I ever ate was oddly in Bangkok, but this is in an area with a lot of arabs so maybe it's not that odd.
http://www.durianseed.com/thailand/bangkok/restaurants/other/sukhumvit/nana/shahrazad-restaurant/ As a bonus there's a hotel down the street. Go to the club in the basement that fills with freelance hookers after the go-go bars close. Interesting place to be a fly on the wall.
I crashed with a friend of a friend and I wanted to thank him by taking him out to lunch. He wanted to go to this place Kalpapruek (sorry can't find much online). Yeah, it's fusion food, it's in a mall and it's a chain but I liked it so much I made a point of going again next time I visited. In the emporium mall easy to get to from the skytrain.
Don't know what your scene is but if you want to do something really fancy check out this place
http://www.banyantree.com/en/bangkok/resort_facilities/dining/vertigo_and_moon_bar My ex took me for my birthday. Definitely pricey by thai standards but would have cost 10 times as much back in NY.
Can't remember what else bc all those crazy thai names escape me. Just go out and make some friends, people there are insanely friendly down to eat, drink and party all night. Khoa son and Phra Athit roads are where a lot of tourists hangout but it's still fun. Go into all the bars and clubs have a blast.
Avoid lady boys and fruit covered in salt. I even drank a salty orange juice what the fuck? Definitely hit up that JJ Market it's every weekend. Singha is the better thai beer and Sang Som in the local whiskey. Most locals stick to Heineken and Johnny Walker (always by the bottle, there's no such thing as shots there).