The Best tour for the wineries in the San Francisco area is:

 http://www.terrifictours.com/sf.html

I'm not sure what I would consider the best winery.

There are so many wonderful places to try and it all depends on what you enjoy.  One of my favorites, Domaine Carneros by Taittinger is an excellent place if you enjoy Champagne.  Francis Ford Coppola has a vineyard. I could list about a dozen.  

I would suggest a trip on the Wine Train, its fun and they have different packages.  Then there are the tours via private limo.  

To help you out, I've included a link in my response.  Hope you find it helpful.

on your own personal palate. Here are some of my own personal favs in no particular order.

Merryvale, Arrowood, and Castelo di Amorosa.

-- Modified on 8/18/2015 8:52:17 PM

If you make it to Santa Ynez let me know.

Head to somona county! We have beautiful, and hundreds, of vineyards...

Enjoy and take a driver if you go to more than one..... please.....    

Jazz

Agree with Jaz - Sonoma County offers some of the best wineries in the World. Platypus Tours and Terrific Tours provide some of the best transport. Santa Rosa - the gateway to Sonoma County wineries is just 1 hour north of the Golden Gate Bridge - have fun!