My two cents:
Download and print a map of the wineries. Traffic has become so congested you must consider your distances and travel speed at 30 MPH even on hwy 29 and Silverado Tr. Adjust your winery/restaurant visits in line if possible so you don’t get pressed for time.
Water, lots of water. At least one bottle of water per winery you visit. Stay hydrated and fed. You will enjoy the trip that much better. There is always one winery you run into where they overpour or kidnap you for awhile, so have extra water.