Suggestions
If you get the chance, you might want to check out Olympic National Park, including Hurricane Ridge, Ruby Beach, and the Hoh Rainforest.
The drive along the Columbia River Gorge is beautiful. There are lots of waterfalls and several nice state parks along the way. Bonneville Dam is well worth a stop. Have you ever come face to face with a giant sturgeon? Free camping is available at one of the dams on the Oregon side....sorry, I recall only that it was well upstream of the coast.
A drive down the coast to Redwoods National Park and watching the Roosevelt Elk are fun.
At Salt Lake you might consider a night out on Antelope Island.
There is national forest camping just west of Yosemite National Park on Hwy 140. I've camped free there a couple of times. Camping inside the park was really good.....forty years ago. Probably still is, though, and you can still get a campsite without reservations if you show up early for the cancellations.
If you don't mind hanging with a bunch of rock climbers at Yosemite, Campground 4 is good. It is just tent camping, but there's a big parking lot; so, WTH, pitch a tent and sleep in the camper. The shuttle bus is really good for getting around inside the valley. Traffic is pretty bad most of the time.
Looks like you are headed down the east side of the Sierras, though; so, you should check out Mono Lake and sprint up into Yosemite from there. There are several state campgrounds all along your route. You might want to check out the bristlecone pines, too. I really like the Eastern Sierras, myself.
There's little of California not to like....except maybe for the crowds and the economy. It will be a fun trip.
Practice good bear safety.
-Buzz