KSKOH,
Sonoma is an hour from me and I haven't spent much time there, mostly because there are excellent wineries closer to me in the Sierra foothills and in Amador (which I could give you some recommendations). If nobody comes through here on the board, drop me a PM and I'll reach out to people I know up there for some recommendations. Bring your wallet, both Napa and Sonoma charge a pretty penny for tasting and the wine is not cheap (which I am).