I'd get out of SF for half a day and roll down the coast to Santa Cruz. The trip down through half moon bay, Davenport etc. When you get there hit Nisene Marks, it's a park where the redwoods hit the coast. Follow up with lunch at Burger in Aptos, or Pizza 1 in Aptos. Both are within a mile of the park. Pizza one has the best sourdough crust you'll ever have. Get the "Corralitos market", to experience the local flavors.