I've always been a big fan of the Center Bar at HRH. There's quite a mixed bag of people and you have a good chance at some fascinating conversation.
This bar used to be prostitute central earlier this century but its cleaned up a little bit. Kind of bummed they got rid of cheap super fun 21 tables on the outer rim. But I do like the new TV's they put at the top of the bar and I still prefer the music at HRH over any other casino in town.