If I only had one day in Napa through a local eye
I get calls from friends all the time coming to the Napa Valley. Most of the time they are looking to crash at my house for a free Napa B&B. Sorry can't help you on that one, but even more of the time friends have someone they know coming to the valley and want them to call me to see where they should go. There are a few questions you should know in order to best customize your trip here.
First, how much are you comfortable spending on a bottle of wine.
Second, do you prefer red or white wines and specifically a certain varietal.
Next, what do you usually drink.
Last, Special requests?
The price of the bottle you are comfortable is extremely important as you probably wont enjoy an $80 Napa Cabernet from Oakville or the Stags Leap District if you primarily drink wines below $10. At the same time, if your wife or significant other loves bubbles, but you don't hit a winery that serves sparkling you could be missing that special something. What you usually drink is also important. I had learned this lesson when a fellow Pepperdine Alum come to town from Asia. While here I was taking him to my favorites when I asked what he usually drinks and he responded, "mostly french wines." Big Napa wines for a typical french drinker can be a difficult transition, so I headed over to Robert Sinskey and a couple houses that have Pinots and nice Merlots. My friend left very happy. Special requests can be hard. I am a big Paradigm Winery fan, but on short-notice it is hard to get in, so not all can be accomodated.
So...If you are only coming for a day, here is what I would suggest. Go for 3 wineries, maximum. Pushing that last one in gets a bit hectic and you can't enjoy the experience. For the locals, we go opposite the flow of traffic. Start with Silverado Vineyards. Get some pictures as it has the best view in the valley. Tasting room staff is great and they have wines ranging from whites, reds and roses, $25-$100+. Sometimes they break out library wines which are fun to taste when you can. Next, continue North on Silverado Trail and swing into Mumm. I have yet to find someone that doesn't enjoy sitting on their deck that overlooks the vineyards. I am not a sparkling drinker, but friends seem to enjoy the experience repeatedly, they even have a nice Chardonnay and Pinot Noir. If you are not into sparkling wines, substitute Mumm for ZD. They have some nice wines for appropriate prices. Great family that owns and operates the winery. I love their Chardonnay and have personally had one of my best tasting experiences here during harvest. Last, cut across west from Silverado Trail to Highway 29 and head back toward Yountville, call ahead, but try Elyse. Ray Coursen has been making some of my favorite wines for a long time. This place is tiny buy awesome if you like Big Reds. He makes Petite Syrah, Zinfandel and Cabernets primarily but other varietals are mixed in and if you like Napa Style wines this is your place.
Please understand, these are wineries that serve Napa wines on the fair side of pricing. There are some great wineries, but for the normal person their wines price them out of the market.
Before you head out, take some provisions. Stopping by Ranch Market in Yountville will help to have some snacks for the road to make you remember the trip.
Once you are done, head to Il Posto Trattoria, a locals favorite. All fresh pasta, and house cured meats. The Il Posto Pie (pizza) is amazing. The arancini and fried castelvetrano olives, stuffed with sausage are outstanding as well. Never had a meal there I didn't love. Call ahead as they frequently fill up, even on weeknights.