It's a cool place to see. I work in agriculture and seeing their vineyards and asking tons of questions about the Ag side was definitely interesting.
I recommend lining up a private tour guide. We used this guy. He lined up 4-5 stops for us to tour with our group of 4. If it's just 2 of you, see if he can match you up with another group they might already have. Not uncommon.
https://www.tripadvisor.com/Attraction_Review-g32766-d1180480-Reviews-Wine_Country_Safari-Napa_Napa_Valley_California.htmlYou can go on your own and tour different vineyards for a $20-30 tour fee and then you buy wine if you want. With a private tour, these tour guides take you to smaller vineyards and you visit with either the owner or someone in the family that owns it. The tours are free,, but the expectation is that you buy a few bottles. So you still spend $25-50 each stop on 2-5+ bottles if you find something you really like.