Basically its Highway 1 down the Pacific Coast from Monterey to San Luis Obispo. Fabulous road along the coast but watch out for where you are going to stop as there are few places and its a fair way inbetween. Not very busy traffic wise but watch out for drivers looking at the scenery rather than the road. From San Francisco to Monterey you have the choice of going down the coast, riding Skyline Blvd down the top of the ridges to the west of Silicon Valley or riding down the valley itself. I would go for the hills - you'll see plenty much better coastal scenery later. Silicon Valley is not a very pleasant ride but if its your thing wandering down from Palo Alto to San Jose and seeing where it all happened and places like the Google, 3Com and Intel campuses and Stanford University is fascinating and awe inspiring. At the other end after SLO its a bit mixed with Vandenberg Air Force Base to get round but after Santa Barbara (go for crab at the end of the pier and visit probably one of the most beautiful university locations in the world along with UBC, Vancouver) you'll find Rt 1/101 to LA has quite a few cyclists on it although not a very pleasant dual carriageway and then you can thread your way down the coast from Malibu (view it from the beach, not the road), Santa Monica, Venice Beach and on down through Newport Beach and then follow the old Highway 101 alongside Interstate 5 from San Clemente to Oceanside and then you are back to having a choice of streets down into San Diego.