I like staying in Yountville when visiting the Napa Valley. You are walking distance from several of the Valley's top restaurants (including the French Laundry) and there are several great hotels to choose from (many with a complimentary champagne breakfast!)
Don't be too ambitious when making wine tasting reservations. I have found that 2-3 good tastings in a day are plenty. I would recommend doing the winery's higher end wines at a sit down tasting - if possible. Once you have had the wines of 2-3 wineries you have had enough wine that you won't be able to judge the real quality after that point!
Check out Greystone the Culinary Institute. They have a restaurant there where graduating students cook the meals and work in the restaurant. it's definitely a culinary treat. The food is great, the wine is superb, and the views of vinerards from the balcony couldn't be more relaxing.