I would add to Nolena's list for hiking the lightning ridge trail that is a PCT section from Inspiration point to Vincent Gap, and of course Mt. Baden-Powell.
For off highway, not off road, the fire roads that cris-cross the ridge between Lytle Creek and Swarthout canyon are great. 2N56, 2N57, 3N31, 3N29, 3N49, 3N33, 2N89. Many of these interconnect and offer route with some spectacular views of the Cajon Amphitheater, the San Andreas fault country of Swarthout Valley and Lytle Creek. Top maps would be Telegraph Peak, Cajon, and Devore.
Also the Forest Service N roads down to Lupine Campground from Inspiration point are real pretty.
I highly recommend the USDA Forest Service San Bernardino National Forest Atlas. Which can be ordered on line.