Marriott is the closest easiest on site airport. For you or anyone else in a similar position in the future at PHL. Can walk from the terminal, no bus needed. Also Minute suites is available post security in PHL but not really ideal for 2 people. Better for 1 person alone, its not really a hotel room, its a sleeping room but offers overnight rates and is very easy if an early morning flight and they are already post security.