bronco peak and that area is cool for the hard core. don't try it with a stocker though. pinion mt is fun, a jeep or smaller will fit through the squeeze but no full sizes. coyote canyon just north of borrego springs is cool. moderate trail but scenic witha cool water crossing. only open full length 10/1-6/31 though. big horn sheep area in the summer.
couple hours up to big bear, lots of trails there too. get involved with a club. there are several so find one you like. get a guide book from Charles A. Wells, Peter Massey or Roger Mitchel. they all have ones for socal areas.
Here is what the squeeze looks like. this year i'll be bringing my cherokee so i can fit through.