Philly on a budget...friend visiting

So I have a friend of mine flying up from Dallas next week, and she's never been up here before. I'm relatively new myself, and while I live spitting distance from NE Philly (Palmyra, fuck I hate Jersey), I haven't done too much exploring around town. I've got a couple obvious things to do (Art Museum, Genos, Liberty Bell/Independence Mall), but I'm not entirely clued in about things to do. Any suggestions?

By the way, Im Military, so I get the Art Museum for free this summer. Also, I'm looking for walking distance from PATCO or SEPTA....I'm 0/2 driving in Philly....first time I was towed from 2nd and Dock, and the second time I got into an accident. I can take a hint.