I’ve stayed at a few different hotels in center city, here are my impressions of their treadmills:
Loews: 6 Cybex treadmills – I’m not a big fan, hard decks, really lame displays, often one was broken, gym opens at 6 am
Marriott Courtyard: 6 high-end Life Fitness treadmills w/ individual TV screens, gym is open 24 hours, very nice
Marriott (deluxe tower fitness room, not sure about main fitness room): 4 StarTrac treadmills, gym is open 24 hours
Update: I’m staying at the Marriot again, but in the main building this time. The main fitness room on the 7th floor is pretty nice. They have 8 or so high-end Life Fitness treadmills w/ individual TV screens, and a couple nice elliptical machines as well. Gym is open 24 hours , has free small bottles of water, and photocopies of a 1.5 walk/run loop. This is the nicest gym from an aerobic standpoint I’ve seen.
Update2: The Philadelphia Airport Marriott Fairfield Inn (on 8800 Bartram) has a very wimpy gym. There is a single consumer-grade Precor treadmill (which was very uncomfortable) and two recumbent bikes. There is also a small set of dumbells.