To begin your pretrip planning, visit the websites of the Wine Country's official tourism bureaus, Visit Napa Valley and Visit Sonoma. Three visitor centers are worth checking out while you're in the Wine Country: the California Welcome Center in Santa Rosa, the Napa Valley Welcome Center in downtown Napa, and the Sonoma Valley Visitors Center in Sonoma Plaza.
The Discover California Wines website has information about Napa and Sonoma wineries in its North Coast section. Other useful websites include those of local associations and wineries and grape growers. Many wineries require reservations for tours, seminars, and tastings. You can book winery experiences through the CellarPass and VinoVisit websites, as well as plan your itinerary. Wine Country and Winery Finder, two mobile apps, give you discounts on tasting fees and provide information about restaurants.