Amish country is OK, covered bridges in the area, tourist traps, etc.
Gettysburg and surrounding areas are nice for US Civil War history (battlefields, 'ghost tours', etc.).
PA Grand Canyons on Route 15 if coming through NY Finger lakes region.
Stop off at Conewengo dam in MD (Just south of PA border on the Susquehanna river) to see Bald Eagles (I think last count were 12 nesting pairs). Then head over the Dam and head down 222 to the Union Hotel for a biker style BBQ lunch.
Should try and ride US50. Pick that up at Winchester VA and ride west to Bridgeport WV. Some nice mountain twists and scenery.