Overview
If you're a huge Zinfandel fan, some of the best Zins can be found in Sonoma! There's a saying in Zins... "The three Rs" which stands for Ridge, Ravenswood, and Rombauer. And for good reason :)
Winery Stops 
Known for Zinfandel. They make better Zins than the ones you find at Trader Joe's and your local grocery store.
The only affordable wine in the 2009 Wine Spectator Top 10 Wines list was a Seghesio Zinfandel.
Can't say enough about Ridge Zinfandel.
Part of the three Rs for a reason!