Big Bear has quite a few trails of varying difficulty, just short of 2 hours from Glendale. East of San Diego, out in the desert is the Anzo-Borrego, Corral Canyon, Ocotillo area with a couple dozen or so trails. Distance there from Glendale is 3 - 4 hours, I'd guess. There's some other areas with trails scattered around, within 1 - 4 hours. Nevada & Arizona aren't that much farther, either, and Moab is only about 10 hours away.
Check out Charles A. Wells' book, "Guide to Southern California Backroads & 4-Wheel Drive Trails". It lists most, but not all of them.
If you come out, I'd suggest that you bring your jeep.