We are headed to Sonoma for a 5 day cycling tour. However, have one night in Napa and day and a half to explore. Any suggestions on wine tour companies. Or how approach. Want to make the best use of our time.
I suggest you contact one or two of the wineries you want to visit for their recommendations on reliable tour companies. Or, check out TripAdvisor. Don't know when you are going, but Napa is expensive, crazy busy, and bumper to bumper traffic.
When will you be going? The Napa Valley does get quite busy during the summer months. I'm sure there is some sort of tour you can find, or if you have a car you can go to wineries on your own. Two wineries that are definitely something to remember are Sterling Vineyards (https://www.sterlingvineyards.com/) and Castello di Amorosa (http://www.castellodiamorosa.com/). They are located near each other in Calistoga.
If you are looking for a nice place to eat and like French food, I love Bistro Jeanty in Yountville. http://www.bistrojeanty.com/
Andrea beat me to it...Bistro Jeanty is fantastic. Not to be missed.
Check out Cline Winery (technically in Sonoma)... free, excellent wine, down to earth winery and very friendly.