Sorry I didn't see this in time! Where did you end up going?
I've been to Firestone, Rancho Sisquoc, Koehler, Zaca Mesa, Foxen... and there was another one I can't remember. We took a limo and did ALL of them in one day. It was way too much and I felt drunk by the 3rd one even though I was only sipping (and spitting many of them out), but it was fun. I thought Koehler and Firestone were the nicest. Foxen was the least nice of all of them (it was like a roadside shack), but I liked their wine a lot.