Overnight in philadelphia- what is there to do?

I would just head to a nearby mall. The main Philadelphia attractions are closed and by the time you get out of of the airport, to the hotel, to the city - it will be pretty late. OR you can rent a car, drive to NY stay out till 2am. Drive back and be at the airport 3 hours before the flight. Or try looking here for places to visit in Philadelphia, Pennsylvania - http://www.tripcart.com/usa-regions/Eastern-Pennsylvania,Places-to-Visit.aspx

There are a few hotels near the airport obviously, but I don't know how much there is to do outside of the lobby bar. You could take a cab out of the airport and into the city, but you're looking at a close to $30 flat fee. You could also take the SEPTA R1 Line into 30th Street Station for a lot less money, and be central to a lot of other places, including the subway. There's a couple of places to eat, a bar inside and a bar across the street from the station. I think the R1 gets close and maybe even connects with one of the hotels down there. Bars in Philly close at 2am, and get surly at 1:30 if it's not a Friday or Saturday. You could take the Market Frankfort Line (Blue Line, The El, etc...pick it up at 30th Street Sta.) and take that to City Hall (plenty of bars), Old City (even more bars and restaurants) or Northern Liberties (even more and just one stop past Old City). Geno's and Pat's are open 24 hours and are good for a cheesesteak, but there's nothing else around there really. Plus, you need to take a cab to get there (cabs start at like $2.30 or something).

Walking around Center City isn't too bad at night; just be careful, especially if you're out late. Since you've never been here, you should try to see Independence Hall and the Liberty Bell. I'm not sure how close you can get to the bell after hours, but you can at least see the outside of the Hall. You can see the outside of the Betsy Ross house and walk down Elfreth's Alley, the oldest residential street in the country. We have some beautiful architecture here, including Old City, Society Hill and City Hall. Walk around City Hall and peek down Broad Street to see the nice buildings they have illuminated in a pretty way. Go into the lobby of the Comcast tower and check out the display on their wall. At first glance, depending on how it's set at that moment, it looks like the rest of the walls in the lobby. Then it changes and it's like watching a drive-in movie indoors. This isn't exactly a rollicking good time, but I assumed that you asked the question because you already know you can just go to a bar and wanted something else. It's also free, except for transportation. Depending on what time you're here and how much energy you have, you could also catch a play or other show at one of the many theaters downtown. Welcome. Have fun!

Stay at the Red Roof Inn or the Microtel near the airport. Both are relatively cheap (under $100 per night) and are in good shape. Honestly, if I arrived at 6pm from an overseas flight (you'll still have to allow time to clear customs) and had to fly out at 7 the next morning (which means you have to be at the airport by 530), I would just grab a bite to eat and crash in my hotel room.