You guys should check out the Palomar Truck Trail...runs west up the back side of Palomar Mountain. Trail head starts off of Highway 79 near the Naval Warfare Survival Training Area.
Views of the observatory, a cool stone house, lots of signs warning of military training (saw a cool Blackhawk buzzing at about 200' off the deck last time), and of course over 40 geocaches along the route (if you are so inclined).
This is a very 2WD do-able run with lots of dust, trees, and rocks. A great day trip for all of you to check out.