I've camped in the area and ridden parts of the trail in 2009 and 2010. Some thoughts:
1. Pettecote Junction Campground at Cedar Run was the grubbiest campsite I'd ever been at, but it's directly on the trail and on the water as well.
2. The PA State Forest sites are free with a permit, but when I used them in 2010 I never got a 'clean' one. Expect to find food and litter tossed and dropped around.
3. I never saw a bear, but they are around - which is why I was disturbed about getting unclean campsites. (My first night on my 2010 trip I camped 20 miles south of the trail next to some rednecks who assured me their Glock would protect them from the bears their messy campsite drew.)
4. If you want to try something different and don't mind climbing, Naval Run campsite isn't that far from the trail and is a couple hundred feet off the river. It's on the Naval Run hiking trail, so you might meet some backpackers:
5. There are 'general stores' along the way, but they can be touristy and pricy. The store in Waterville is popular, but I recall them as the only place I've ever been to that gave me dirty looks when I asked them if they would fill my water bottles for me.
6. The Bike Route G splits from the trail just north of Waterville. I suggest sticking to the trail and avoiding the road traffic and small rollers. The trail spends a few miles on the other side of Pine Creek, but much of the distance to Jersey Shore it runs parallel to the road.
7. The best views of the Pine Creek Gorge are from above, on one of the rims. That means climbing or getting a lift. The road leading to the west rim of the canyon is less than one mile from the trail, but the overlooks are about 3-4 miles up that road. If you ride, do so with care, since drivers are probably not looking for bikes.
8. If you ride, or get a ride, up to the west rim, take a short walk along the West Rim Trail, a 30 mile backpacking trail. Some of the views are spectacular.
9. Scott Brown - the photographer, not the MA Senator - in his book on Pennsylvania's Mountain Vistas says in dry weather it's safe to photograph beyond the safety barrier at Barbour Rock. He's right. But it's a little nerve wracking for someone afraid of heights.
10. While there are bald eagles nesting in the canyon and Little Pine State Park near Waterville, they aren't that easy to spot. You are more likely to see turkey vultures like these in this photo I took on the west rim: