It has been a few years, but when we went the greatest experience was at Del Dotto. The guide toured us through the caves pulling wine directly from the barrels with a long glass thief. He had as much fun as we did as he compared the same wine at different ages, did back to backs of similar wines to compare and contrast, and was just very generous with his pours. I don't know how he he did it all day long because he was drinking as much as the tour.
Most of the wineries we went to had their high points- great wine, beautiful views, rich history, but Del Dotto was a tour we talk about when ever someone asks what our favorite winery was in Napa.
If you're looking for something less bacchanal, Jarvis has a stunning network of caves that alone is worth the price of admission.
Enjoy your trip,
Del Dotto Wine Gallery
1055 Atlas Peak Rd, B Napa, CA
2970 Monticello Rd, Napa, CA