Start from the viewpoint to San Francisco Golden Gate Bridge, down to Sausalito, then follow the coast to Mill Valley. Mostly downhill for the first part, then mostly flat. Another beautiful ride in Marin County.
Note: This could seem a bit slow for a road ride, it is because I was on my Enduro mountain bike with big knobbie tires and low pressures. Couldn't keep up with the roadies, sorry.
Check my playlists for more rides around San Francisco or in the San Francisco Bay.