If you want to drive along the coast, it will take twice as long as the quickest way, which is Interstate 5. The coast highway is not always open all the way through due to rock slides. It is one lane in each direction, winding and narrow. If you get behind a slow driver, and you will, you will be stuck for hours until the next turn off. It would be fun, but slow. I have stayed in Monterrey and Carmel, but they are both a couple of hours out of San Francisco. If you are looking for a midway place to overnight, that would be near San Luis Obispo and Santa Maria. I recently did the Pacific Highway along the coast from Santa Barbara to L.A., it was great.