You can get commercial information from NapaValley.COM.  For years, I found The Best of the Wine Country to be a useful guidebook to the area, but it’s out of date now.

Wine

Wine is the first order of business.  There are more than 400 wineries in the Napa valley, and more than 600 if you include Sonoma county. I have visited only a small number of these wineries.

Many wineries now charge between $25-50 for a tasting flight. Some offer tours, meals, or other attractions on site.  Most wineries have club membership with requires receiving shipments every 2-3 months. Members of the wine club typically get access to special events and free tastings.

There are a small number of wineries that offer free tastings or will wave the tasting fee if you purchase 1-2 bottles of wine:

• Buehler Vineyards, St Helena hills, Free but tastings requires reservations
• Heitz Cellar, St Helena, Fee waved if 2 bottles purchased
• Sutter Home, St Helena, Free
• Vincent Arroyo, Calistoga, Free tour and tasting for groups less than 4. Reservations required.

The Wine thief in Napa down the street from the Oxbow Market, is a wine shop that does tastings from a number of the smaller, independent operations. Well worth a stop.

Some of my favorites wineries

• Hess Collection (Napa, decent wine, small interesting modern art museum)
• Cuvaison (my favorite wine)
• Sterling Vineyards (Catistoga, tram to great view – wine not so good), 
• Hall (Saint Helena, some art, very good Cabs)
• Castellodi Amorosa (13th century Tuscan Castle, some tasty Italian style wines. La Fantasia is perfect drink for turkey sandwiches the day after thanksgiving, or casual outdoor parties).
• Clos Pegase (Catistoga, some interesting art).
• Frogs Leap (Rutherford, well done wines, good environmental stewardship)
• Mumms (Rutherford, good sparkling wines)
• Warm Springs Ranch (where the desktop picture on OSX Sonoma is from)

Sonoma / Mendocino

• Korbel Champagne (Russian River, nice flower garden)
• Buena Vista (Sonoma Valley, nice picnic area)
• Toulouse (Anderson Valley, Pinot Noir excellent, Gewurtraminer is nice)
• Fogline (Santa Rosa, My favorite Zinfandel)

Food

There are a large number of excellent restaurants. Many of these restaurants participate in “Restaurant Week” at the end of January where meals are provided at a discount rate. The Oxbow market is a high end food court, mike the ferry building in SF, North Market in Columbus, etc. Several interesting restaurants and food stores but nothing amazing.

Activities

Check of napa valley events for seasonal events and activities.  There are a number of popular activities in the area:  bicycling, hot air balloon rides, mud baths in Catistoga, etc.

Lodging

There are countless B&Bs in the area  Many are mediocre, but there are some which are outstanding.  There are some amazing resorts which are amazingly expensive like Meadowood, Bardessono, several Auberge Resort properties. Slightly cheaper include Napa Winery Inn, Harvest Inn, Kenwood Inn, El Dorado, and Honor Mansion.