There's a Marriott directly attached to the airport so no need to even go outdoors to go to your gate. I've never stayed there myself but mentioned it to a traveling temp/coworker who wrote us back that she loved the convenience.
We've parked at Winner Valet and while I love that for returning, they bring my car right to the airport all warmed up for me, I didn't like how fast our driver drove when taking us from their lot to the terminal at drop off. It also kind of creeps me out that they have my keys and my registration has my home address and they know we're away and when we're returning.
Maybe that's just me cuz lots of people here rave about them.
http://www.longtermparking.com/penn.htm
We like PreFlight Parking. Their shuttle picks you up right at your car, drops you off at the terminal. For return, their shuttle comes every 5 mins so it's never a long wait. They drop you off right at your car. There are coupons in the mail (Valpak if you get those) for $7-something per day.
Compared to the airport's Economy Lot which has a bus shuttle every 20 mins and you get a huge tour of the parking lot before finally getting dropped off within a 1/4 mile walk to your car (jk, lol!) and they charge $11 per day.
http://www.phl.org/directions.html
If you don't want the Marriott, Expedia is a great search tool. It's easy to use to find hotels around an airport, then I book directly with the hotel.
