I checked the book Monongahela National Forest Hiking Guide (8th ed, 2006), and the Allegheny Mt Trail seems to be rated strenuous do due the northern 25% of it which we wouldn't need to hike in a loop. The portion we would walk is an old forest service road which is still used only by them for maintaining fields for wildlife. The scenery is rated as "exceptional".
The Lumberjack Trail is the other option for making a large loop. It's rated as moderate, and the scenery is "exceptional-wooded" (meaning don't expect views). This trail sounds interesting because it has several springs, streams, and sinks where the stream goes underground.
If we're energetic and have time, one option would be to do an out and back up to Spruce Knob on the Huckleberry Trail, gaining about 1800 ft up to 4840 ft in 5.8 miles. The book rates the scenery on this trail as "exceptional."
Just more options to consider. So many trails, so little time. :)