St. Helena is the heart of the Napa Valley wine country, a small town of around 6,000 people strung along a single Main Street about 30 minutes north of the city of Napa. It sits between vineyard-covered hillsides on both sides, and what makes it different from the other Napa towns is that no chain businesses are allowed — the downtown is a pleasant mix of independent restaurants, wine shops, and boutiques.
The town is best approached as a base for winery-hopping rather than a destination in itself. Dozens of acclaimed wineries are within a short drive in either direction along Highway 29 and the Silverado Trail — including the historic Beringer Vineyards, Charles Krug Winery, and Spottswoode Estate. The food scene is serious — some of the valley's best restaurants are here, anchored by the Culinary Institute of America at Greystone, and even a simple picnic lunch from a local deli with a bottle purchased at a tasting room will be memorable.
Note that weekends and harvest season (September-October) bring heavy traffic from San Francisco. If you're visiting on a summer Friday, plan to arrive before 2pm or after 7pm to avoid the worst of the congestion.