About 20 miles south of Mendocino, California in an area called "Manchester" is a KOA that we'd recommend. Nice shaded sites, well kept, clean bathrooms, ice cream social nights, nice pool. They used to have these bikes you could rent that resembled "big wheels"... even adults could ride them.
If you are into collecting driftwood, they are within a couple of miles of one of the best (Manchester state beach) driftwood collection beaches on the west coast. Of course.... for those who are full-timing, just what you need is more stuff to cart around!