Here's a little airport secret: the holdover restaurant.
Every concourse at Philadelphia International has such a place, which will stay open past the usual 10 or 11 p.m. closing time if flights are delayed because of mechanical problems or weather, or if the airport is just generally busy.
When you're stuck at the airport late at night, these holdover restaurants may be open:
Concourse A: Olde Philadelphia Tavern.
Concourse B: Cibo Bistro & Wine Bar, Jet Rock Bar & Grill.
Concourse C: Jet Rock Bar & Grill.
Concourse D: Lamberti's, Jet Rock Bar & Grill (opening in late summer).
Concourse E: Jack Duggan's Irish Pub, Bassett's Original Turkey & Salad.
Concourse F: Jet Rock Bar & Grill.