Anonymous wrote:We did this with kids of similar (a little younger) age--I posted about it here if you search. It was a great trip but better for the adults than the kids. We ran into heavy traffic most of the way, which I was not expecting. Definitely do Hearst Castle, you will be so ready to get out of the car by the time you get there. When we went back a few years later we flew between SF and San Diego.
PP here, wanted to clarify my heavy traffic comment. The issue was that the road was under construction and single-lane for many stretches, so we had to wait (up to 45 minutes, so not just short waits) and then follow a flag car through the single-lane stretches. It got really tedious and old, especially when we were hot and wanted to get out and stretch our legs. I don't know if this is a common thing in the summer or we were just unlucky, but the drive took us longer than we'd thought.