Graham,
After crossing the Golden Gate, I suggest taking 280 South to San Mateo, then 92 West towards Half Moon Bay. After just a few miles (way before HMB) turn south on 35, aka "Skyline Boulevard":
http://en.wikipedia.org/wiki/Skyline_Boulevard
Stop at Alice's Restaurant in Woodside for lunch, where "you can get anything you want...":
http://alicesrestaurant.com/index-6.html
Proceed down Skyline to the intersection with Highway 9. Take 9 South towards Santa Cruz. This takes you right into downtown, along River Street...
Markus