I did a little scouting around today for another good meetup. Whilst cruising through the northern Jim Thorpe area (love that town), I stopped into a little restaurant, and the waitress staff there told me about this place. Glen Onoko has some real interesting trails, but the tunnel sounded really cool to me, and the distance sounded pretty good for all types of hikers (about 5.6 miles). Read more about it here: http://gonehikin.blogspot.com/2011/05/glen-onoko-fallsbroad-mountain-lehigh.html
It is a little far to be considered "Harrisburg", but I find some of the best stuff is worth the distance.
Weather is unpredictable, but I think the temp is great for this. Love that time between Summer's end and Fall's beginning.
Following the hike, I would recommend The Beacon restaurant. A decent veggie burger was available there (good tzatziki sauce). Plenty of choices for the non-veggie crowd too.
See what you think, and looking forward to meeting all who can make it!