Just a little story of our trip "out west" with our children. In 1989 we loaded our two daughters, ages 13 and 9, and our little dog into our 22' motorhome and headed west from Maryland. Our trip was pretty much drive and stop to see what comes along the way. We rarely spent more than one night in a campground except the Grand Canyon, Yellowstone, Durango, Zion/Bryce area and Rapid City. We were on the road for 5 weeks. We rode the train in Durango, took a mule trip into the Grand Canyon, rode horsees in Yellowstone and Rapid City.
We did what time and money would allow. The girls handled all of the driving well and look back on the trip with many memories: good, funny, and not so good (stranded briefly on the Indian Reservation by Canyon de Chelly).
They never complained about the driving as they knew once we stopped they could run off energy in the campgrounds making new "friends" along the way.
We carried activities for the time in the motorhome and usually stopped during the day at some attraction (Fantastic Caverns, Walnut Canyon, Meteor Crater) that only required a few hours to break up the drive. This was before the advent of video games, ipods and ipads so they actually spent time enjoying the varying scenery.
So the purpose of my rambling on is to say, grab your boys, climb in your motorhome and go on your trip. If you find that time is not working out, you can always alter your route. Yes, you may be disappointed that you have to miss something, but in the end what will be remembered is what you did and what you saw, not what you didn't. We never got as far as California. Our girls didn't miss not seeing California because of all that they did get to see.
Go, Have Fun, and let us hear about your trip.