If you have the time I would stay off Geary Blvd. What I am suggesting takes you through some places where there is a lot of foot traffic and some route finding issues so don't do it if you're not ready to be very slow and careful.
When you get to the top of the hill after going past the Cliff House, do not proceed straight onto Geary, but take a left at the light on El Camino del Mar and then the first right on Seal Rock Drive which turns into Clement St.
Turn left into the Golf Course at 34th Ave. and pick up El Camino del Mar again by turning right just past the Legion of Honor entrance and fountain.
Stay on El Camino del Mar until it enters the Presidio and becomes Lincoln Blvd. You can get right onto the GGB from Lincoln Blvd. but the Presidio is a National Park and you might want to look around.
If nothing else, drive out to Fort Point and touch Hopper's hands for luck on the rest of your journey.