Best way through San Francisco South to North.....

I agree with Pnichols that it's best to avoid SF entirely. At San Jose, take 880 north, past Berkeley to the San Rafael Bridge. In San Rafael, head north on 101. This route may still be slow, but it's far less crowded. Stay as far as you can from SF. It is a great place to visit (and live!), but not in a motorhome.