Favorite vineyards/tasting rooms (from a trip to Napa): Vinter’s Collective (tasting room in Napa features small wineries without tasting rooms), Carneros, Du Mol (great Pinot) Del Dotto (wine caves), Krug, and Grgich Hills.
Our favorites: Mumm, Chandon, Rombauer, Patz and Hall, Hess Collection, Sterling (aerial tram!), St. Supery, Frank Family…
I definitely concur with putting Rombauer on your list! The $25 tasting fee for 5 (?) pours is also a bargain.
Others:
Cakebread
Caymus
Heitz Cellar
Opus One (I’ve known Robert Roux, their VP of Sales, since 7th grade)
Quintessa (Silverado Trail)
Robert Mondavi
Whitehall Lane
I highly recommend getting off the main drag (Hwy 29) and hitting some wineries on the Silverado Trail!
Edit: Don’t assume you can just show up. In many instances, you will need to schedule your tastings.
What kind of wine to you like? When are you planning to go? How long?
Fall is the harvest season – so it will be very busy and expensive. If you want to see wine making “in action” then that is the time to splurge and go. But if you hold out to the first week of December, it’s much less crowded, cheaper, and the weather is still decent.
Napa is a pretty good small town. The Andaz is a nice hotel. It will give you a bit of a “city” feel. Napa is a big with Cabernet Sauvignon. I would definitely hit Rutherford Hill Winery – up on a hill, great view and cool caves. Markham Winery mixes in artwork – when we went they had a bunch of classic rock photographs and such.
You might also look at Sonoma, a bit smaller and more laid back. The Inn at Sonoma is a nice place walking distance to the square. I found a better mix of wine types on that side especially in the Carneros region between Sonoma and Napa. In that area hit up Nicholson Ranch winery. The owner has a great story – Former Indian tech guru decides to make wine. Roche winery has a tasting room right off the square which is pretty good.
As for visiting wineries, it depends. If you have large group and someone is willing to be designated driver, that can work. We did a wine tour thru Platypus wine tours. Our guide was Sam, a local farmer. They take you to 4 wineries (not the touristy ones), feed you lunch, and get you home. Other people also just hire a driver.
If you’re up for a drive thru the country, head north toward Healdsburg. Just outside of that town is Coppola winery – owned by the Director Francis Ford Coppola. It’s a pretty cool place. They have a bunch of movie memorabilia, like a museum. They also have a nice restaurant and decent wines. We took a whole day trip – winery, lunch, shopping in Healdsburg.
Both kids and their spouses visited Napa wine country numerous times and they joined wine tours where they didn’t need to drive themselves.
I live in the Bay Area so I’ve attended many weddings at different wineries but since I don’t drink alcohol I can’t make recommendations.
I actually like the town of Healdsburg in Sonoma county … close to wineries but a fun place to stay. We went zip lining in the redwoods not too far from there - https://sonomacanopytours.com.
Or in Napa Valley, go get mud baths in Calistoga - https://www.indianspringscalistoga.com/mud-bath-spa/mud-mineral-baths
Fall is a great time to go (assuming no big wildfires) - really pretty colors, nice weather still.
@jshain - we are Rombauer club members. Free tastings are so worth it! 
Yourmomma’s review is spot on. Rutherford Hill is a great winery. Just below it, there is Rutherford Ranch. We like their Predator wine (the ladybug on the label is the predator they refer to).
BunsenBurner, Several times my wife and I have chosen a restaurant because they have Rombauer Zinfandel on their wine list.
We did a great trip 6 years ago. If you search this Forum you will find the thread.
Our favs - the bike/wine tour https://napavalleybiketours.com/
Lunch at CIA https://www.ciachef.edu/cia-california/ ( this was our best meal) We also took a class.
Schlamsberg was worth a visit ( need reservations) Also liked Sterling and Frank Family.
We stayed at Villago in Yountville- mentioned up thread. I think I got the recommendation from CC.
Have fun planning!
“Redd is now closed! Bummer…”
@jshain, the “sister” restaurant Redd Wood (more casual) is still open.
Haven’t been in a long while be really enjoyed having lunch on the wine train. We were lucky enough to stop at Grgich Hills and watch the nephew overseeing crushing grapes. He talked to us at length and was lovely. Very cool to be there during crush.
We also had great visits to Ferrari Carano and Chateaux Souverain (in Headlsburg).
We stayed in Sonoma at the Mission Inn and Spa. Lovely restaurant there and of course spa services ; )
I don’t drink at all, but once win a while I drive visitors over. Most popular place is Robert Mondavi. Visitors also like to go to Yao Family Wines and take a picture of a life-size cutout of NBA Hall of Famer Yao Ming. Haven’t been over there though since the big Sonoma County fires from 1.5 years ago that destroyed quite a few wineries both in Sonoma and Napa counties.
Monterey is really a lovely vacation destination, and I would choose it in a minute, but I think you would really like Carmel by the Sea. It’s s short drive from Monterey, so you could combine the destinations. Carmel by the Sea is a delightful, artsy,upscale destination with great restaurants and shops. We only spent a few hours there, but would love to go back. Do some research on it and see if you might like it.
Same with us @FlyMeToTheMoon . We only spent a few hours in Carmel, but said we’d love to go back for a few days.
This part of California should not be missed. Took what seemed like annual vacations down there when our kids were young. Besides Monterey Bay Aquariam and Cannery Row, Pacific Grove, the 17-Mile Drive, Carmel, Point Lobos, Pacific Grove are must-sees, but our favorite is the drive from Carmel to Big Sur and just south. Spectacular! The crown jewel of places to visit in our great state, IMO. We spent countless hours near Asilomar State Beach in Pacific Grove and overlooking the fire pit at Nepenthe. Great, tranquil times…
Carmel and Monterey are wonderful places to visit. We spent 2 weeks in Carmel one summer and two weeks in Pebble Beach another summer when D was showing horses up there. Just beware that summers can be cool. That’s why we liked taking the horses there in July to escape the Southern California heat.
Just agreeing/“sharing the love” for Carmel and Monterrey, and other areas around there.
Wonderful area, with lots to to.