Just as a word of caution, if you're going to travel the California coast in June you may have a difficult time finding RV spaces without reservations. And overnight parking is prohibited almost anyplace you would find a spot big enough to pull off on.
Another tip, I don't know your total route, but if I wanted to tour the west coast like you're doing I would prefer to start in Seattle and go south. Most of the things you'll want to see and the places you want to stop are on the ocean side of the road. If you're in a motorhome most of these places will be impossible to get into while going north.