All depends what you are looking for.
If you want 3 great wood coasters, one steel invert, one wild mouse, one boomerang, and a fair selection of flat rides, take Hershey (though for a single day, it could be a frantic pace... especially if you wan rerides).
If you want 1 great wood coaster, and 1 even GREATER wood coaster, a great haunted house, plus some good flat rides, and a nice laid back and slow pace, take Knoebels.
Depending on your travel directions, as someone said above, you may want to make a slight detour to Lakemont Park in Altoona (or since you live near Pittsburgh it is an easy day trip). A small but fun wooden coaster (Skyliner) with wild airtime on its first drop, and the FUN Leap-the-Dips.
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"I wasn't always this cynical, but then I started kindergarden..."