I did it last August/September, Bellingham to south of San Diego. It's easy to ride directly out of the Bellingham airport (I've done that twice). It's a great ride. Lots of hiker/biker camp sites, so it's a great route to camp. You can read more about my trip in my journal. I averaged 60 miles a day. Big Sur is the best, but the whole route is fantastic (although it gets quite different south of Santa Barbara). I suspect, however, that due to the severe California drought, you may find that many of the California state park campgrounds have closed the showers--bummer! Wash yourself off at the water spigot or jump in the ocean.
Have a great time.