Happy 21st! Just remember Thailand is nothing like Bali just much better!
If you run amuck in Bangkok like some Aussies do in Bali then you will be frowned apon by the locals and maybe arrested.

there is so much to see and do in Bangkok that when you get there you will wonder why you even asked this question.

there are some great bars and clubs,top end low end and sleeze.stay away from the sleeze and you wont get upset but do visit Patpong as its great for both sexes with good markets to boot.

Do not buy or take drugs of any kind in Bangkok,if you get caught buying taking or already taken you will be arrested (Just thought i would slip that in)

You can party in Bangkok like any city in the world but it isnt bali or Kuta so you must show more respect than perhaps some would in Bali.

Have fun.

Den