Ohiopyle is a lovely state park. Older sites though. But nice up in the woods. A good number of of electric only, no full hookups. We have and will stay there. We prefer the "more natural" state park environment. As others have noted there private RV parks available too. To each there own.
While there, don't just visit Fallingwater (which is great) but also visit the close by Kentuck Knob
. It's only a few miles from Fallingwater, just outside the state park entrance, on the other side of the town of Ohiopyle.
Have a good time, the small town of Ohiopyle is cool too. There are also some neat caverns
nearby that are worth the trip if you like that sort of thing. They are very "natural", lots of fun. Different from say Luray Caverns (which are also cool, but in a different way).
Don't know which way you are coming from, since you live up the road (from me) in Hanover, I assume you might take I 70/I 68/Route 40. If so, there is a STEEP hill heading in and out of Ohiopyle, just brake at the top and take it easy, you'll be fine. If you decide to stay at the state park, there is an alternate route on you can use (I think it's on the park website) where you can avoid the steep hill while towing(that route actually takes you right by Kentuck). You still have to head down a steep hill to get to Ohiopyle, but you'll be doing that without the trailer if you camp at the SP.
Have fun, it's a very nice area no matter where you stay! Book soon as Oct. is a very busy time.