In Marin County in Larkspur, there are multiple options. If you want to go to one of the strangest yet best executed restaurants I can imagine go to Roxanne's. A fantastic wine list is available to go along with the "raw food" (cooked by sunlight etc.) Charlie Trotter is a fan of the cuisine.
Bradley Ogden's Yankee Pier is close by and is really an excellent well priced restaurant. It is Bradly Ogden's take on an upscale east coast seafood shack.
A few doors down from Yankee Pier is Bradley Ogden's flagship restaurant - The Lark Creek Inn. Superbly executed California-American cuisine. A very nice wine list including well priced rarities like 1997 Marcassin Estate Pinot Noir for $200.
My favorites restaurant in Marin County is way out in Inverness. It is worth the 20 mile drive however. Inverness is right on Tomales Bay. In Inverness, there is an old turn of the century hunting lodge called Manka's Inverness Lodge. The restaurant is open to the public. The sommelier has great wines - I mean really great wines - at reasonable prices. The food comes from only local purveyors. Five course fixed price meal. No menu you get what they are cooking that evening (a la Chez Panisse). Every dinner I have had there has been great. Ask to be seated at the Chef's table. The Chef's table is for eight and usually is filled by multiple groups of diners as opposed to a single large party. More of a tasting menu is served at the Chef's table.
For casual dining, Sam's is great to kick back at and enjoy the water.
Left Bank Larkspur is also worth a stop. It is my favorite location for Left Bank.