if you like to dance....any of the gay clubs around 13th and locust, sprcue and sansom are great! especially woody's! long time fave of any girls night out...
dinner at a larger BYO in the city is probably the best bet for a big group of people with different tastes.. Mellagrano's, Branzino and La Viola are the best ones off the top of my head. this way you can bring your own beverages and enjoy the best italian byo's in philly.
jolly's is a lively piano bar on chestnut....dont' know what the crowds are like on saturday nights though.
even if you don't want to go to the gay bars, your best bet is the 13th and sansom street area as there is plenty to choose from. great bars, dance clubs (time for example).
rooftop bars include vango lounge, continental and a few others. i think vango would be a fun loungy atmosphere. there is another one that escapes my mind at the time.
for karoke, yakatori boy in chinatown has a great setup...you don't get on stage and its very chill!
enjoy :)