I've driven a heap of California (I'm from Australia and done two road trips). Highway 1 from San Fran to LA is an incredible drive, and you go through some cool places like Big Sur and those old redwood forests. There's good places to stop too, but I found that in all parts of America the difference of a few blocks is monumental.
Also I've used AirBNB a lot and fully recommend it. You can rent entire apartments or a single room. And you get to stay in cool areas that you may miss on tourist routes.
Also as mentioned above, Yosemite is like a painting it's that pretty.
Vegas is fun. Then it becomes not fun. It's like there's millions and millions spent on make some giant fire-spewing volcano and next to it is a dude injecting heroin with his family (I actually saw that). It's a hell of a town and well worth seeing, but I found the poverty overwhelming at times.
All that said, I've been planning on moving to LA this year. California is brilliant...