The Korstian division is probably the largest tract -- it offers many options of varying length and difficulty. The walks along New Hope Creek are great from November to May, otherwise may want to stick to the popular trails unless you don't mind chiggers. There's a nice ascent up Piney Mtn which can be reached most quickly from Mt Sinai or Irwin Rd trailheads.
Dina P. on Shepherd Nature Trail
Fine for a local Hike......watch for dogs off Leashes. Do everyother week.