Between just Sonoma and Napa Counties there are hundreds of choices so you have to come up with a criteria to narrow the selection.
|Here's one way to get around|
on your first visit.
Image from limo4winetour.com
If not you may want to start with a tour at one of the big boys like Mondavi or Beringer. If you've made a trip to Napa already it's time to branch out to Sonoma or somewhere else. If you're already been to Sonoma, Santa Barabara, and the Sierra Foothills maybe it's time for Mendocino or Santa Cruz.
Do you know much about wine?
If you consider yourself a novice you may want to stick mostly to names you've heard before such as Mondavi and Beringer, but don't be afraid of some places you've never heard of because you'll find that 99% of the winery names are new to you.
What time of year are you visiting?
Napa Valley and anywhere close to a large city can be very crowded in peak season. This can detract from the overall experience. Choose somewhere less famous and you'll get better service.
Do some Googling before you go.
Do you prefer certain varieties?
Certain wineries and certain growing areas are better for certain types of wines. That is, Chardonnay and Pinot Noir grow in cooler areas with a coastal influence and Cabernet does best in warmer areas. With California's micro-climates you can still find most varieties within an easy drive of each other, but if you love Zinfandel you want to visit Dry Creek Valley, for instance.
Looking for new wines or things you can buy back home?
Some folks want to sample so they have a better idea what to buy at home. Others are looking for only wines they can't find on their local store shelf. You see Beringer, Mondavi, Kenwood, and Chateau St. Jean wines everywhere, but even these big boys make a few wines you probably won't find at home. There are many small operations that you've never heard of and these are where your new wine discoveries can be made.
What price range of wines are you interested in?
You probably shouldn't be stopping at Sterling if you are looking for high-end Napa Cabs. Likewise, you probably don't want to make appointments on Diamond Mountain (where you find expensive Cabs) if you are looking for cheap Chardonnay.
Or are you not buying this trip?
You can stop in tasting rooms that are open daily or you can make appointments at smaller wineries where you sit down with the owner and/or winemaker. If you're just sampling to see what you like with the intent to buy back home then stick to the open-to-the-public tasting rooms.
Once you can answer these sorts of questions it becomes easier to make recommendations and for you to do Internet searches to find potential stops.