Being the dark, cold month, the desert is the only reasonable choice. I've done a lot of riding around Death Valley in the dead of winter, and it can be great. In fact, this year, for the third time, my wife and I will be cycling from Lone Pine to Las Vegas via DV. Some parts of this tour can have lows below 20 deg. F. in mid-winter, but the highs are often in the mid-60's. When weather comes in, it's usually strong winds out of the north. And they can kick some ass, I'll tell you. One of the all-time great tours of North America is the Lone Pine to Palm Desert run: http://ridewithgps.com/routes/217987
This gives you the best of the Mojave Desert--Death Valley, East Mojave Preserve, and Joshua Tree National Park. Go prepared for long distances between water/resupply points, be ready to camp in wild, isolated places at times, and expect the greatest, grandest desert fantastica anywhere. I LOVE this tour. You need to work out transport. One way would be to leave a vehicle in Lone Pine and rent a Uhaul in Indio or Palm Desert to take you back. Check it out. Bad. Ass.