I know what you mean. And all in all, it's got more to do w/ being w/ a bunch of people you appreciate and enjoying the moment. When the music isn't that loud, it makes it easier.
But then all the rest sort of becomes incidental - drinks, music and all the rest are just part of a great moment you share w/ folks.
I'd be lying if I said I'd never had good times in bar, but more often than not, we could have been in a restaurant or at home or whatever.... And the rest of the time, as you say, I'm usually just looking for an excuse to leave.
I remember the premiere party in Moscow last year - the coolest part of the evening is the part we spent discussing w/ a few guys in the band, outside the club, smoking and drinking a beer. The minute we walked in, it was boring as heck after a couple of minutes (yeah, even w/ free drinks and all)...