Go to the BLM website and look up Johnson Valley OHV area
http://www.blm.gov/ca/barstow/johnson.html . It's about 150,000 acres, and it's probably about an hour from you. That's where I do the majority of my riding/racing. In fact the Checkers MC are having their hare & hound out there tomorrow, and that's where I'm headed.
Here are some simple directions to get you there. Take I-15 north like you're going to Vegas. Get off at Bear Valley Road/Lucerne Valley. It's like the first exit past the the HWY 395 exit. Keep going east and follow the signs towards Lucerene Valley. Once in Lucerne, just keep heading east, the signs will probably say something like Yucca Valley/29Palms. The first sign you will come to that will say something about Johnson Valley OHV area will be Camp Rock road. Camp Rock Rd is the first of 3 access roads and will get you riding the fastest. It will be a left, as all the access roads will be, and just follow the signs. Eventually, if you take camp rock, you will end up at Anderson dry lake staging area. There is a sign there with a big map to show you where you're at, and the boundaries of the riding area.
If you didn't turn on camp rock and you kept going, the next turn off you would come to is Bessimer mine road, again there will be signage that you can't miss. After that there is Boone road that will take you to Means dry lake, I don't reccomend this road unless you have 4 wheel drive as there is some pretty deep sand in a couple of sections.
Our club race (Huntington Beach Motorcycle Club) HBMC is coming the weekend of 3-11/3-12. I am running the kids event on saturday at 3 pm in the afternoon. You are more than welcome to come and check out the scene, but, I'll be kind of busy that weekend but, I'm sure I can find sometime for you after the kids race or on Sunday.
Feel free to give drop me a pm and we can hook up. You have to drive a bit to get the area's here in cali, but, there is plenty of riding to be had.
Hope this helps,