Napa Valley is about 1.5 hours north of San Francisco and easy to reach from the San Francisco, Oakland, and Sacramento airports. If driving from San Francisco, the route over the Golden Gate Bridge, then west through the Carneros Valley is a much lovelier drive and a better introduction to wine country than the congested shopping mall corridor of American Canyon (Route 29). A convenient shuttle bus run by Evans Transportation gets you to Napa from the San Francisco and Oakland airports. And quite a few tour companies offer reasonable rates on day excursions from San Francisco.
Public transportation is limited in the Valley. A bus called The Vine runs up and down Highway 29 between Calistoga and Napa throughout the day for about $1.50 a ride. With winetasting a main attraction to the area, tour companies are popular and can be surprisingly affordable. Many tour drivers have relationships with wineries that are off the beaten path, reservation-only, or otherwise little known or exclusive. Be sure to tell your driver in advance what kind of experience you are looking for, and he or she will likely make good recommendations. Take note that the Napa Valley Wine Train is not really intended for transportation: It’s a half-day trip up and down the valley that includes lunch and a winetasting.