California is a large state!
Which end of CA do you need to travel to? If LA:
Take I-76 to I-70 all the way to St Louis, then I-44/I-40 to LA. Start early, and quit at a decent hour each day -- you don't need to plan your stops ahead of time, there are cities and towns from one end of this route to the other that will have more services (gas, food, lodging) than you can use. You can do this in about 37 driving hours -- so that's about 3 days and some change (driving at normal highway speeds and 6 AM to 5 PM, not including any breaks or other stops. I say start and stop early because this is the summer travel season -- it makes it easier to get a decent room if you beat the crowd (and driving in the early morning is very nice). Other than that, keep it loose, and enjoy the drive. Getting there is ALL the fun! Bob