The best advice for exploring wine country is to plan accordingly in order to maximize you time. There are a lot of places to go and almost all are open from just 10am-5pm. All of the wineries that offer tours do so only at specified times...check ahead of time so you get the most out of your time and aren't waiting around like we did at several different places. Also, have an idea of what type of wine you enjoy drinking...this will help you from wasting time and money tasting wines you don't like. I prefer semi-sweet to dessert wines and didn't bother tasting the dark red dry wines--which is mostly what is grown in this region. This helped when I wanted to purchase because I focused my tastings to styles I know I enjoy.
By far the best tour and tasting is off the beaten path in Sonoma at Korbel. This was the best experience we had in wine country. They offer free tours and tastings and their tour is fantastic! It was the best historical tour we had. Our barkeep and tour guide was Gunter and he was extremely knowledgeable of Korbel's history and 'spirits'. He was also the friendliest person we met on our trip. Korbel produces champagne, wine, sherry, and brandies. We tasted a little of each and ended up buying several bottles to take home. The winery is situated in a beautiful area with mountains and redwood trees all around. The scenery is spectacular and the gardens are open for tours mid-May. We didn't make it to any other wineries in Sonoma because we spent nearly the entire day there. They also have a great little restaurant on-site, as well as a deli for picnickers with great shaded outdoor seating.
While in Napa, we visited just four wineries: Robert Mondovi, V. Suttui, Niebaum-Coppola, and St. Supry. Our first stop was Mondovi's. This is the best place to go for a tour of an operating winery. We actually have done that many times and decided to go for the quickie 30-minute overview tour. We were escorted through the vineyard and given an overview of the growing process. Next, we went into the cellars and saw the fermentation tanks and the aging barrels. Our guide was very informed and did give us a lot of information about Mr. Mondovi, the vineyards, and the Napa Valley. The tour ended with a tasting at which we were given our glass to keep. The whole thing cost $10 and you can only go into the vineyard and winery on a guided tour. Although the basic tour is acceptable, I would recommend the full hour--it's more in-depth and a better use of your time.
Our next stop was Niebaum-Coppola winery. This place should be a stop if for no other reason than to view the gardens and beautiful buildings. This place also had--by far--the BEST gift shop! It's huge and has a lot of great items, definitely a must for goodies to take back home. The women working at the bars were very nice and honest about the wines available for tasting. They gave us specific selections to try by the glass and saved us $10 each on a tasting. The tasting does include a beautiful wine glass--I suggest it if you are a dry red wine lover! The winery has a small museum on the second floor with movie memorabilia dedicated to Francis and Sofia's movies. It's worth the 10 minutes, especially if you are a Godfather or Apocalypse Now fan. The only thing missing from this winery is a tour--but stroll through the gardens and enjoy the Italian feel of the surroundings. Don't miss this winery.
St. Supry was the biggest waste of time in all of Napa! They have a self-guided tour upstairs that is unremarkable and the tasting room has a very lame gift shop. When we attempted a tasting, we were treated very poorly. The staff was snobby, condescending, and rude--which matched their insanely high tasting fees which ranged from $10-$25 per person. We ended up leaving disappointed and angry because of the way we were treated. Also, the "garden tour" is actually a basic marked walk around the front yard. All in all, this stop was a total waste--don't bother unless you are a big fan of their wines--you'll be treated better elsewhere.
Our final stop of the day was at V. Sattui. The barkeeps were incredible and the wine was great too. The man who was doing our tasting was extremely busy, yet we felt as though we had his attention the entire time. The tastings here are free and the wine is excellent. We purchased six bottles to take home. The best part about this winery is the picnic-friendly atmosphere. They have a plethora of shaded tables and a deli on-site. We had purchased a bottle from the cooler and took it outside and had our dinner. V. Sattui wines are only sold at the winery so be sure to stock up!
The one winery we regretfully missed was Beringer. We were told by staff at many wineries that it is by far the best tour in Napa. We came into Napa from the south and it is located in the north part of the county. Plan your stops accordingly...you will want to go there.