Like everyone esle, it depends. Corral Canyon is almost always a one day run. I can go from town, run a couple of trails and drive home on one tank of gas. but it's very cool camping there and getting in a night run up there, great views on clear nights. And yes, the lower/bottoms campground is the better of the two.
For desert trips, it depends. On longer weekends I like to go to Superstition Mt OHV, dry camping, but awesome trails.
http://www.blm.gov/ca/st/en/fo/elcentro/recreation/ohvs/superstition.htmlOutside the summer months I like to camp at Aqua Caliente . Full hook-ups so I can have my A/C or heat as the case may be and catch the race or game on Sunday on DirectTV and enjoy a dip in the spa in the evening. Close to some fun trails in the south desert.
http://www.co.san-diego.ca.us/parks/Camping/agua_caliente.htmlIf, and it's a rare if, I'm going to in the Ocotillo Wells area than I usually stay near Main St or way down east of Pole Line Rd. I really am not a fan of that area, way too many people with more money than brains. My question about that area remains: who lets their kids (little kids) ride quads at 3am through the camping area?
I had an incident thre a couple of years ago when a kid on a quad ran into me on blowsand, fortunately I was just sitting there and he wasn't really hirt, but that happens a lot there. But if you want to drive fast, it's the place to go.
http://ohv.parks.ca.gov/?page_id=1217If you really want to get away head up to Coyote Canyon and camp at the entrance to the actual canyon. You can spend a week there and be lucky, or not, to see another person.
http://www.desertusa.com/mag00/apr/stories/coyote.htmlFor trips to areas like The Squeeze I dry camp at Blair Valley, a dry lake bed, but there's enough moisture there so it stays much cooler at night than the surrounding desert
http://www.desertusa.com/anza_borrego/du-abpblair.htmlOK, too much information, maybe I should write an article about camping in SD county... ;D