If you consider W. PA, there a several options. In the Highlands just southeast of Pittsburgh, you can visit Fort Necessity (built by G. Washington after his English forces and Indians murdered a French Envoy) to attempt to repel retaliation by the French, Fallingwater built by Frank Lloyd Wright, white water rafting at Ohioplye State Park, or bike the rail to trails to Washington DC. A short distance away is the Flight 93 Memorial, and the Johnstown Flood National Memorial. A couple of hours east is Gettysburg, and then on to Philadelphia area for Independence Hall and Valley Forge. If you have kids with you, consider a stop in Hershey that has an amusement park, Zoo, botanical gardens, and Chocolate World. Not far away from Hershey is the Lancaster area, home to a large sect of Pennsylvania Dutch (Amish & Mennonite), quaint villages like Bird-In-Hand, special dining options, and other things.
Good Luck with your trip planning.