Back on topic to the OP...
There are so many places in SoCal to head out, and timing is everything.
Check out the parameters of posting up a run, and visit the SCCX Desert Xcursion Archive area to get an idea of where the club has traveled.
Several of our members (Frank B., Paulxyz, Soylent Yellow) have great Anza Borrego knowledge and have posted some pretty detailed run reports and photos.
Click here:
Desert Xcursion Archive for more information.
Good luck, and hopefully you can draw a few people out of the woodwork to hit the trails with you!