Our campsite at Granite Pass
Our first day was spend driving from LA to Granite Pass, which is off Highway 40, north on Kelbaker Rd. (add link to maps and Google Earth Here...). Beautiful granite formations reminiscent of Joshua Tree, high-desert cactus abound. Still too low for a significant number of Joshua trees however, except at the absolute highest part of the pass.
There are a very nice set of camp sites a mile or two off the "main" road which are accessible by 2WD if you are careful. Boring driving if you have 4WD. I have no idea how popular they are, there was one other car there when we camped in mid-June, which is well after the normal spring wildflower rush.
It is a fairly high altitude (~4500 ft) location, which is cooler in spring and summer, but can be quite cold (I've been snowed on before) in the winter. It can be quite windy in the winter and spring (Kelso Dunes are only a few miles away), when there are significant pressure gradients.