We just got back a couple of weeks ago and already want to go back!
Since you are staying in Calistoga, head towards Healdsburg/Alexander Valley one day to visit Jordan (Estate Tour - it's worth the money) and Hawkes.
I agree with Del Dotto in St. Helena, but I strongly recommend you do the Delicacies Tasting and this be your last stop of the trip. You won't want to go anywhere else afterwards.
Hendry (owner's tour) - This is a good tour for casual wine drinkers up to medium level wine connoisseurs. A history of the winery, a walk through production, and then a scientific style tasting. George will kill your palate and bring it back to life. Your tour fee goes 100% towards purchases.
Biale - We all know Black Chicken is great, but we enjoyed The Founding Farmers just as much for $10/bottle less. Appt only.
Provenance - excellent and unique Malbec Ros, but the other wines fell flat. Worth a stop, but not a special trip just for this place. I know - I'm in the minority regarding this winery.
Alpha Omega - nice setting, but the wines are way overpriced and fall short compared to others we tried on the trip. I know- I'm in the minority here again.
Domaine Carneros - Decent and iconic, but I would skip this one and try Chandon or Mumm.
Chandon - very relaxing to sit on the lawn while tasting. Better quality sparkling wines than Domaine Carneros, too.
Food: check out La Luna one day in Rutherford for a quick lunch. A Mexican grocery store with a taco stand in the back.