I've been the last 2 years in November. Awesome place with so much to do. I stay on Sukhumvit as opposed to the usual Khao San Road which is the backpacking area. Ive stayed at Nana hotel and Bel Aire Princess with the latter been alot better but alot more expensive ( i only stayed here because it was part of the flight/hotel deal ). Nana hotel is opposite Nana plaza, the heart of the party. That's Bangkok btw.
If you need any help at all dude drop me a PM and i'll try and answer any questions.
Also a trip over to Koh Samui is a must imo. Can get a flight for around £60 with Bangkok Airways.