Take 101, the scenary is beautiful. Here are the wineries of my choice in Napa. Girgich Hills, Whitehall Lane, Opus One, Caymus, Peju, Silverado, Rombauer, Rudd, Silver Oaks. Whitehall and Girgich close around 4.30-5 and Peju is open till 6. Rest close around 4. Most of the wineries let you test for free but most the above mentioned wineries will charge you somethig. Opus One is $25 per taste. If you can get a wine list from a restaurant and can talk about wine, then they will treat you differently and might not have to pay either. If you go to other wineries, make sure you try their Cabernet. Napa has the perfect climate and soil for Cabrenets.