Logan Circle is another spot that is famous Philly landmark but sometimes not familiar for its location.  The fountain and statue (Swann Fountain) is a great backdrop for photos and is located in a nice spot right in the middle of the Parkway next to nearby locations like the Basilica or The Logan.  For engagement sessions, its a nice stop when doing photos by City Hall and possibly heading towards the Art Museum.  You can get some great shots along the walkway around the fountain or if you're feeling brave, inside the fountain as well.