I think they go there to hang out with their friends. These are places where they can dress/doll up, in whatever they like and be with their buddies to chat, chill-out, and maybe drink/get wasted (some do). Meeting the opposite sex, well, maybe some of them ladies might, but I don't think that is the main purpose for most girls. I do not know of girls who go to clubs on their own, it is either with a bunch of friends, or with a date they already know from before.
Cheers!