Kentuck Knob and Falling Water are about 3 miles west and 4 mile north of Ohiopyle, respectively. If you want to do some hiking, Ohiopyle is a good place. There's very easy walking on the Great Allegheny Passage (a rail trail that follows the Youghiogheny River in the Ohiopyle area), and plenty of real hiking nearby. You can rent bikes (or bring your own, of course) and ride on the rail trail, and you can take a very easy rafting trip on the middle Yough or a more challenging trip on the Lower Yough if you want a bit of excitement.
While the Laurel highlands encompasses a fairly large region, Ohiopyle is only about 35 miles from Ligonier, so you could see both Kentuck Knob and falling Water and be in Ligonier by mid-afternoon if you wanted.