Check out the sticky thread on this section "Car cruises in your area" if you haven't already, nice site that lists a lot of cruises in calendar date order.

Sept 17 at Pittsburgh Raceway Park (New Alexandria, Route 22 east), is the PID-Keystone Nostalgia Nationals. There is a car cruise as well, and car and driver are admitted free. It's going to be a good show on the track, and should be a good show in the cruise too. Lots of neat stuff last year.