If you are flying with Air Asia, just book the hotel at the same time via their flight + hotel option. Its cheaper and very convinient.

On the food, you must try:

1) Somboon Seafood (http://www.somboonseafood.com). You will never go wrong here.
2) Crab meat "khorn lor mee" - situated in Silom (cant remember which lane) but it is at the road side next to a Japanese restaurant.
3) Chinatown - must try the seafood there (just go to where the most ppl are eating and you will be safe).
4) Durians - Excellent

These are the few that I will surely eat when I am in Bangkok. Will be going in Sept. Waiting for AA cheap tickets.

It is not expensive. Reasonable and not cut throat. Its clean and delicious. I tried the Bangkok and Chiang Mai branch too

The Chiang Mai branch has 5 floors!

Packed with ppl, mainly Thais and some tourist. Food and service is good. I heard it is owned by some royalty in Thai, which go back in history. Highly recommended.