I agree that having your own vehicle and making stops between Las Vegas and Los Angeles is ideal. However there have been posts regarding driving RV's in Los Angeles as part of a longer road trip and posts from "young" drivers. The reinstated MegaBus might be an option for those who want transportation between these two cities. Has anyone tried it? (Bay area destinations will also be available.)
I haven't used it on the West Coast, but I have used their Midwest Service a couple times. I thought it worked well. It can certainly be a bargain, if you buy tickets early enough - as the bus fills the prices rise. The fact that it is express service, going directly between major cities, without all the intermediate stops in small towns is a nice advantage over Greyhound.
I will say its also impressive how they have grown in the past couple years. Not too long ago, Megabus was basically a spoke and wheel system with routes based out of New York and Chicago. Now, its grown enough where there is some overlap, and you could actually use Megabus for longer trips across much more of the country.