S.P.
I would highly recommend the Grapeline tours in Temecula. Depending on where you are in Orange County, it's not that far. They offer a shuttle tour to about 4 or 5 wineries. The tour is about 10:30-4:30. The tour guides are great and the atmosphere is fun! AND, they are reasonably priced. I've taken the tour a few times (romantic weekend with my hubby, girls weekend, and a bachelorette party). I definitely recommend them. If you're in the northern part of LA, look ino the Grapeline tours in Santa Barbara. Same company, but I like the Temecula wineries better.
Oh, and the almond champagne that Holly mentioned is at Wilson Creek! Yummy!