Dogs are allowed at some local California State beaches. (This means on the beach not on the bluffs above the beach.) For a list click Dog Beaches.
Too many to describe:
Click here for a list of city and county parks, including the above and a few others, like ones in Rohnert Park.
Click here for a brochure of parks in Petaluma, including Rocky Memorial mentioned above.
Badger Dog Park, 750 Heron Dr. Healdsburg. Best for small dogs.
Sonoma Dog Park, 175 First St. W., Sonoma.