Bangkok and Hong Kong are probably neck and neck as far as ex-pat populations go. The HK ex-pats are wealthier though. HK and Bangkok are both sexually and socially very open cities. Pattaya is in a different league altogether, although there are plenty of rich ex-pats in Pattaya, Bangkok is still a corporate city, so I guess it still generally attracts a more "upmarket" type of ex-pat.