Hey yyemporor,
I'm actually a Penn ME undergrad right now so I thought I'd give my input on its program. I can't say anything for Columbia but at least I can let you know a bit more about Penn's ME.
The Wharton advantage you listed is definitely true.. many engineers (undergrad at least) come here dualling in majors with Wharton because it's obviously a very good opportunity. There's a pretty good grad program in both engineering and wharton here called ENTM, if you haven't checked it out maybe you should!
It's true Penn doesn't have a big name in engineering. But I actually think its ME has a very up and coming program. In the few years I've been here the ME department has been making huge turn arounds, and it seems to be restructuring its program to be more like stanford's. I don't have much personal experience with solid mechanics except to say that i had a good undergrad class, so I can't say much for what the grad program and research is going to be like. But imo the ME program here definitely has a forte in robotics, which has been acquiring new faculty lately and making sizeable impacts in the field. And in general, i've seen that student-faculty relationships are such that you'd have no problem at all finding alot of professors to 'deal with you', esp for grad students. i think you'll find yourself surrounded with very dedicated and interested faculty.
And as for Philly.. true.. pretty boring city. Unless, you like food and the arts, then you'll find yourself suitably entertained. (although NY obviously still > Philly on these fronts) But then again NY is also $20 and 2 hours away, and i personally go there often enough. Cons are that if you're not looking at Columbia because its 'dangerous'.. you'll have the same problem in philly what with its sharing borders with west philly. nooot the safest place. annnd it is unfortunately true that no one around the world really knows what 'penn' is unless you say 'wharton'. But, in conclusion, i've definitely enjoyed my time in the ME program here, and i personally extremely appreciated the kind of academic basis it gave me, with the balance of focus in labs and in depth theory. but the surroundings have worn me down enough to say i'm glad to leave for west coast grad school next year.