I am totally flexible on Sat 2/21. I won't get in until midnight to previous evening, so I'm not looking for a 6:00 a.m. wake-up call.

But meeting 10 am or thereafter is DO-able.
As I mentioned, I will not have a car, but could easily take the subway to Philly.
I do not know the area at all, so I will leave it up to you (or others who might join in) to make suggestions on where to meet.
I need to be back at the airport by 3:30 pm at the latest.