We have an 8 hour layover in Philly for our flight to Miami. Am I consigned to the inner circle of hell (aka the airport - any airport) for my sins? Or could I realistically take public transit or? to Philadelphia and at least see Constitution Hall? Or am I cutting it too close?

If all goes well its a 30 minute cab ride into center city (Philadelphia). Certainly enough time to see some of the sites. http://gophilly.org/ can help you with hours and locations ... and an extra plus is that you can pick up food at the Reading Market for the flight to Miami.

regards,
sheryl

You can take the airport train into center city also. There is plenty of time to visit the historic areas or other places - e. g. run up the art museum steps - with the time you have.
The trains run about every one half hour and take about 20 minutes from the terminals to center city. The historic district is east of center city near 5/6th and Chestnut.
I second the Reading Market idea for your take out dinner to Miami.

Mary, avvocato is right. Take the Septa regional rail train (R1) from the airport right into Center City. Probably best to get off at Market Street East. If you'd like to get a quick overview of the city, try riding the Philly Phlash, our hop-on/hop-off trolley loop. It will take you by many of the main sites in Center City. Costs a $1 each hop, or $4 for an all day pass.

I wholeheartedly third the idea of buying some food at Reading Terminal Market, which is at 12th and Market Sts, one of the Phlash stops and easily accessible from the Market Street East stop.

Although you'll only be in the city for a few hours, there may be some information here that may be helpful for you.

Hope you enjoy your quick visit. You didn't say when you were coming?