We hired Tac to drive us around Napa just last week, and we couldn't have been happier! We were a party of four and two of us had never been to the area or on a wine tour before. Tac is SO knowledgable about Napa, wine, and the people who create them! He customized our trip around the type of wines we drink and set us up with a place to have a picnic lunch at one of the wineries. He took care of the table outside and set our food out while we sat inside sampling wine (and paired foods!. He took us to Robert Biale, Robert Sinskey (where we had lunch but not before eating their paired tray of FANTASTIC food!), Viader and Frog's Leap, which was a perfect casual ending to the day.
My advice for a first-time Napa tourist:
Step 1. Hire Tac. He is smart and fun, kept us on schedule, and got us everywhere we needed to go in one piece,
Step 2. Of the wineries we visited, Biale was good, Sinskey was fantastic, Viader was AMAZING with the cave tour and views (and get Chante for your tour, he is awesome!), and Frog's Leap at the end of the day was a perfect casual ending.
Step 3. Pay Tac when he gets you back to your hotel and tip him handsomely, because he deserves it!