North of San Francisco, about a 45 minute drive, is the quaint village of Stinson Beach.  Refugees moving north of San Francisco founded the village in 1906, after the Great Quake.  They built stores and hotels.  After the Golden Gate Bridge was finished in 1937, the community was known more as a beach resort because of the three miles of sandy beach.
The beach area has a park -picnicking area and nearby restaurants to pick up take-out food if you want to have snack before walking the beach.
If you are a bird watcher, be sure to visit Audubon Canyon Ranch to learn more about the bird watching locations and the bay area Herons.  It is located on Highway 1 just north of Stinson Beach.
If you continue on to Point Reyes National Sea Shore, a good place to stop for coffee or lunch is the village of Inverness on the western shore of Tomales Bay.
Driving north about 45 minutes from Stinson Beach in West Marin is the picture perfect coastline of Point Reyes National Seashore.  The preserve has wild costal beaches and headland estuaries.  As you are driving, you will see historical ranches and dairy farms.  At the western end is the Point Reyes Peninsula and the Point Reyes Lighthouse.  Be prepared to walk the tour buses and cars park in the lower parking lot.  Once you have finished the walk up to the welcome center, you can walk down to the lighthouse; however, it is 308 steps down, but then you have to come back up! 
The observation area above the lighthouse is a popular place for whale watching from January through March, so bring your binoculars—the views are breathtaking!

If you prefer a different return to Sausalito or San Francisco, one way is to drive north up the East side of Tomales Bay through the town of Point Reyes Station and the Village of Tomales.
In the 1870’s, Tomales was a stop on the North Pacific Coast Railroad, connecting Cazadero to the Sausalito Ferry.  This is a very picturesque drive along Tomales Bay, so have your camera ready.
From Tomales Drive to Petaluma, you can enter onto Highway 101 and drive south about 32 miles to San Francisco.
Petaluma is well worth a visit.  It is one of the oldest cities in California, with one of the best preserved historical downtown areas.  They offer walking tours of the noted landmarks for you to learn more about the history of the city.  Your walk will take you around the Petaluma River Downtown Historic Harbor.  You will see shops, galleries, and fine restaurants on your walk.  Perhaps this charming town may delay your return a little bit!