No car needed - great suggestions from the group - in historic area, the Portrait Gallery is a must see in my opinion.
The barnes foundation requires advanced reservations and is a must
The franklin institute has the Lego Art of the Brick through September
For uniquely Philly go to Jims on South for that cheesesteak and then to the Magic Gardens
The Mural Arts tour by trolley or foot give you a glimpse into the city (the Love letter tour is via the El train)
For odd philly go to the Mutter Museum for medical oddities
For food reading terminal (metropolitan sour cherry sea salt chocolate chip cookie, and the roasted pork from DiNic's) as well as UBahn for local brews, graffiti bar for hidden drinks and McGillian's bc oldest pub. Make reservations in advance even if a hold for dinner as many small restaurants and full during week
Hotels -monaco has roof top bar stratus and Palomar is in middle of food/Rittenhouse area
have fun!
I have a few other things on my blog