Autumn is the best time to head to California Wine Country, only an hour or so from downtown San Francisco. But which to choose, Sonoma or Napa?
The most obvious distinction is size. Napa Valley dwarfs Sonoma Valley in population, in the number of wineries and in the sheer volume of tourism and traffic. Sonoma is far more rural, and offers a more genuine, away-from-it-all experience. Small, family-owned wineries are Sonoma's mainstay; tastings are low-key, and they come with plenty of friendly banter from the wine makers, who often do the pourings themselves. But even though Sonoma lives in the shadow of far more famous Napa, its wines have actually won more awards.
If it's a serious R&R experience you're after, you'll probably be happier staying at one of Sonoma Valley's secluded inns and perhaps touring the valley by bike--most wineries are located down quiet, gently winding, wooded roads. Sonoma is still an unpretentious gaggle of ordinary towns, ranches and wineries that welcome tourists but don't necessarily rely on them. If, however, you're really intent on learning something about the wonderful world of wine making, Napa Valley may be a better choice. World-class wineries such as Sterling and Robert Mondavi offer the most edifying tours in North America. Napa has more big-name wineries, many more spas (at cheaper rates), and a far superior selection of fine restaurants and resorts. To misquote Gertrude Stein, there's more there there.
For a fuller look at California Wine Country, I highly recommend Frommer's pocket-size California Wine Country guide. Yes, I'm prejudiced, but I trusted my own vacation to it, and would recommend it to my best friend.