I didn't know about the Lear at KDEN mentioned by @paflyer . It is probably in a part I don't go through. I go through there anywhere from twice to 5 times a year.
I don't think PHL has any airplanes inside its terminal but the airport is also part art museum with many artwork on display throughout all the terminals. Every so often they change and display new artwork. There is also a small stage in the B/C Food Court for musicians and singers to perform.