If you came here for Soi Cowboy and Nana Entertainment Plaza, Soi Patpong in Silom offers more of the same. If you just came out of Bed Supperclub and want to continue your night the superhip way, Silom is also the way to go.
Unlike most foreign travellers, the locals tend to go out in Ratchadaphisek. You might want to check out Royal City Avenue often abbreviated as RCA, an entertainment paradise with bars, clubs and theatres, or one of Ratchada's popular 'sois'.
Quite similar to Sukhumvit and right next to it is Siam Square, Bangkok's hippest shopping and entertainment district. It is only a 10-minutes Skytrain ride.