Donnie,
play what 21 year old girls will dance to, if they wouldn't dance to it don't play it. If you get them to stay the bar will not thin out, they will stay and dance and that will keep the guys hangin' out, buyin' drinks, the club will love you and ask you back ( don't make it rocket science, cause it ain't). Totally different philosophy than being an artist, but that is a success formula for a cover band in bars. ( don't take it hard that the folks that are there, are more there to hook up and hang out than they are there for you, just do your best to entertain them and make some cash doing it)good luck...Moker