Very scenic in fall and winter. In summer the trees are very dense.
McConnells Mill State Park, an old gristmill built in the 1800s is open for tours. The gorge has steeps sides and the valley floor is littered with huge boulders and is a national natural landmark. Just remember that Slippery Rock Creek got her name fro a reason. Very slippery rocks. I almost broke my leg a mounth ago hiking there.
http://www.dcnr.state.pa.us/stateparks/parks/mcconnellsmill.aspx
Moraine State Park, a large lake with rolling hills by the lake shore. Fishing and boating are popular. There are many hiking trails as well.
http://www.dcnr.state.pa.us/stateparks/parks/moraine.aspx