Ah, sorry. I just read you were after nightlife. Sanur is pretty sleepy after dark, bar a couple of pubs. Kuta is where you can go if hordes of sunburned drunken Aussie twenty somethings vomiting onto overpowered speakers is your thing. Fun bonus: a beach that is half brown sand, half washed up plastic refuse. Erk. Sorry. It's up there with khao San road in Bangkok for me in terms of just how massively us whiteys can destroy a good thing.
But how do you really feel? Don't hold back.