In addition to everthing Mr SR71 saided, I think you might like the
Mutter Museum. But I don't know how much time you have for any of all that stuff.
Word on the skreet is that the best Philly Cheesesteak is actually in New Jersey, but far enough away that a weekend trip won't grant enough time to get there. As in, it's a half day thing to get there, get it and get out. And that's on top of wonky hours for the joint to boot.
And consider this poste another vote for the Reading Terminal Market.
And if you're of mind, have the time, the historical stuff is worth looking into. (The Liberty Bell, Independence Hall.) You know, cradle of the nation and that jazz.