Sonoma in March

Public transpiration north of S.F. is there but not convenient and probably wouldn’t take you where you’d want to go. 1) Ferry to Larkspur 2) bus to San Rafael 3) SMART train north to Petaluma, Santa Rosa (but not that much to see/do where the Smart stops). If you are talking town of Sonoma, wine tasting, or Sonoma Coast, I’d recommend renting a car for a day that you can pick up in SF.

Definitely a car or a tour. Just a heads-up, March can be rainy in the Bay Area, and the northern counties usually are the hardest hit.

Agree w Rosalyn, rent a car or take a tour. Public transportation in the counties north of SF (Marin and Sonoma) is terrible. It can also be beautiful, warm and no rain in March, no way to know.

You could take a Golden Gate Transit bus to Mill Valley (closest town north of SF w a good car rental co. Mill Valley is appx 5 mi north of the GG Bridge) and rent a car w Enterprise which is very close to the bus route.

Sausalito is south of Mill Valley, located at the north end of the GG Bridge and worth time to walk through the very charming downtown which is on the Bay.

You could also take Golden Gate Ferry from the Ferry Bldg (fun place) to Sausalito, a beautiful and scenic 30 min ride, and take a taxi from there to Enterprise in Mill Valley (appx 5 mi north).

A car is pretty much the only practical way to do that. Depending on where you're staying, and traffic, it's a 1-2 hour drive each way. March is a pretty good time to go, especially if you stay away from weekends. With all the rain this year it's going to be green.

It’s about 40 min to Sonoma County and about 50-60 min to the town of Sonoma from the GG Bridge if not heavy traffic.
You’ll be going opposite direction of commute traffic which is good.