Really depends on your interests and points of travel, I guess...
HD Factory Tour in York Pa is pretty cool.
Straub Brewery in Saint Marys is neat (and free samples from "The Eternal Tap")
Zippo Factory in Bradford if you have interest.
Altoona has the Horseshoe Curve if interested in Railroads and such.
Bill's Bike Barn in Bloomsburg (fee here).
Pa Grand Canyon in Wellsboro Pa.
There is some great eats (not chain or fast food type places) in Pa also, again, depends on your tastes and likes/dislikes.