Easy couple mile loop around Lake Lenape park in Sellersville/Perkasie. There's a steep hill (elevation change 80ft) right across the bridge over the creek that leads up to the community pool facility. I've seen a few people carrying loaded packs up and down it for training. Nice views of the creek!
I've explored Perkiomen Creek (Menlo Park) from the old Mood's Covered Bridge to the exit by the Washington House in Sellersville, PA. The walking path is nice, however you are subject to other walkers with dogs, bikers and loud teenagers. Geese frequent the area and you might see a box turtle or two on occasion.
This trail is actually in Oaks/Collegeville/Schwenksville PA...the southern end is in Lower Perkiomen Valley Park and the northern end is in Green Lane Park. Great bike ride but pay attention to the signs for the trail in Collegeville as it goes right through town.