We are traveling from San Diego through Yosemite and into Billings, Montana. From there we were going to head to Mount Rushmore in South Dakota but have a time constraint at that point to be back in ...
The most direct route is to come down through Salt Lake City and just take 15 all the way into So Cal. That is mostly on the freeway but it's also a very scenic route with lots of stuff to see and do, especially if you like desert.