I've been wanting to take that trip. Pacific Grove, Big Sur and of course the Redwood National Park come to mind.
What's with the geographical dislocation here? Yellowstone is in Wyoming, and worth the trek. New York is on the opposite side of the country. The Op was asking for SD to SF. I'd suggest to the next trekker, or OP if she hasn't done it, to go further north: Mendocino, Avenue of the Giants, Ft Bragg & Glass Beach, even Arcata and beyond ( but not in harvest season, it's too weird)