Philly's a great town and you'd have to try really hard to find a place where you'd feel uncomfortable during the day. Try any hotels downtown or on the Main Line (they'd have a City Line Ave. address).
If you're looking for something to do, there's a great bar scene in Old City (basically between Arch and Walnut and Front and 6th). Make especially sure you check that out if you're here for the first Friday of the month, but it's also where the rock bars and the dance clubs are.
The chances you'll go into the neighborhood where all the students live is unlikely cause there's no real big destinations there, but if you want to see what there is to do in that neighborhood, check out Main Street in Manayunk (across the river from the Main Line hotels). It's like a 5-10 minute drive from where most of the students live and it's pretty cool.
Find a visitor's center or a Wawa and pick up a map of the city. It's shaped pretty much like a Y. In the center is (duh) Center City, laid out nicely on a grid with interspersed parks, plenty of restaurants and stores, theaters, and concert halls. Look a little ways north, on Broad Street, and you'll see where the Dental school is, at Broad and Allegheny. The airport's way towards the South, along with the big concert venues, and the homes of the Phillies (got messed with by Texas), Eagles (gonna mess up Dallas), 76ers, and Flyers. Going to the Northwest, you see Roxborough, which is where most of the students live. It has the largest inner-city park IN THE WORLD, and the main apartment complexes are one big roll down a hill away. Biking, hiking, horseback riding, fishing, jogging, swimming, it's a great park. Thanks, FDR.
Oh, yeah, there's a lot of historic crap too. Nah, it's really pretty cool. Check out that National Treasure movie. Other movies filmed in Philly: The Sixth Sense (Fairmount), 12 Monkeys (Fairmount), Fallen (downtown), Se7en, Witness (30th Street Station)...ok, so those are all a little scary. But what about Philadelphia, Rocky pts. I-V, and Superbowl 39? Quality. Oh yeah. Gotta love Philly.