Thanks for all the helpful replies. It looks like the Windsor is probably our best bet for this trip, seeing as the Residence Inn and Embassy suites have no availability.

Is there some major event in town 11/13 to 11/16? ATC, I'm finding very little hotel availabilty.
It looks like we should be able to walk to the Academy of Natural Sciences from the Windsor, is that right? Their famous dinosaur collection is my son's main reason for going to Philly.
As for driving: I'm not nuts! We'll be coming to Philly via Amtrak from DC, and flying out, so for 3 days, I plan to use transit, like the PHLASH, or cabs.
Any comments on Fairmount Park / Smith Memorial Playground? Is that a relatively safe area for walking?