I just went on a day trip to Philly a few weeks ago with the girlfriend and kids.
Absolutely do the terminal Market. Food is amazing. I had a cheesesteak from Carmens and it was good.
Highly recommend the Observation Deck.
https://phillyfromthetop.com/tickets.html
We did the Observation desk at the Rockerfeller center in NY...The philly one is better.
I want to go see the Eastern State Penitentiary. It's one of the most haunted cool prisons in the country.
Obvious the Rocky Statue and Art museum steps....Great photos from the top.