I was born in Philly (yea Jefferson Hospital!), raised just outside of Philly, and attended college just outside of Philadelphia. I can honestly say that there's such a great integration of culture, history, food and fun here - I go to Philly practically every weekend, and I'm very sorry to be leaving actually 🙁
Anyhoo, definitely hit Old City - 2nd street has the best restaurants (Lamberti's, Serrano, Sassafrass Cafe - the list goes on and on) bars (Paradigm) and clubs (Glam et al). First Friday is great too: on the first Friday of every month, you get free admission to the galleries in Old City area - it's usually pretty packed. Delaware Ave is best for clubbing (Egypt, 8th Floor and such), and South Street is good for just hanging out with friends (south st. diner has great late night cheap eats) and has lots of nifty little shops and eccentric crowds. Check out the Ben Franklin Parkway Museums - Franklin Institute Science Museum, Academy of Natural Sciences...and def. see the Philadelphia Museum of Art! If you are a history buff, go to Independence Hall and see the Liberty Bell in the Historical District. Watch an Eagles game in their new stadium (E-A-G-L-E-S eagles! So close to the superbowl this year: DAMN Tampa Bay ) If you like ice skating, go to the Penn's Landing River Rink (or if you are at Penn and don't have time to get off campus, Class of 1948 Bldg has a rink). And Chinatown is also fun - lots of Great food (Penang on 11th street is one of the best fo shizzle) and stores.
I almost wish I wasn't going to NY 🙁....so Yes yes YES you will have PLENTY to do!