I did my seminary studies in Latrobe, PA. There's some catch and release trout fishing in nearby Ligonier, PA on Loyalhanna Creek. A fairly tight stream, but access/wadeability is easy along a little city park.
Very picturesque little stream that runs through a beautiful gorge all the way through to Latrobe. Mill Creek joins it at Ligonier and also has trout.
Ligonier's a neat little town, very historic (complete with an old British fort you can walk through), and has a couple of flyshops, including an orvis dealer. It's worth a trip in itself.
I never fished it, but the Youghigeny river (sp?) has an excellent reputation, though I'm not sure about access. It would be closer to you.
Here's a helpful link Fly fishing Pennsylvania Rivers and Streams