My girlfriend and I went to the Buena Vista Winery outside of Sonoma for one of their standard tastings. Overall, the location is gorgeous and it is incredibly close to downtown Sonoma. I encourage you to have a big lunch in town and then head out to taste some wine. Be prepared for a little bit of a wait before you are able to get a spot at the bar for a tasting.
Full disclosure, I thought the wine was average and the pours were a little short. But the experience was still pretty solid. We bought a bottle as a gift for my parents, and they certainly enjoyed that.