Last summer I camped in Confluence at the Army Corp of Engineers campground. Well done site just below the dam so you have white noise from the river to sleep to. For holders of a Senior Pass, it's half price.
I camped at Connellsville at the free site on the west edge of town. Best of the lot on that trip. Pitched my tent inside a shelter and slept snug as a bug. Lovely quiet spot. Grocery store just down the hill.
I also camped at Rockwood. LOVED the hot shower after 4 days riding in August. Yes there was railroad noise all night. Some sort of switching operation on the other side of the river. May bother some folks, not others. Nice campground.