The Philadelphia scene pretty much has everything to offer that you could want. Honestly this is probably one of the best times during the year to visit. Philly is really great in the spring.
The gay scene in Philly is pretty much self contained in what has been affectionately called "The Gayborhood". The city actually added rainbow colored plaques beneath the regular street signs. Once your there you pretty much can't miss it. There are lots of bars and lounges to hit. That neighborhood actually has some really amazing restaurants too. Amis, Bindi, Lolita, El Vez, Raw, Tria, etc. There are probably 3 quintessential Philadelphia gay bars to not miss. Woodys is the classic pub style gay bar that has a big second floor with a dance floor. Q is your basic queeny lounge. They do make some good fun drinks though. Then there is Voyeur, formally Pure. This is your afterhours warehouse style club. There are lots of place to go other than that, but they seem to be the most popular during the week.
I don't consider myself an expert and I personally don't go out much. Its not really an issue with my desire, I just work a lot and would rather chill with my friends and sleep when I can. Hope you enjoy!