M.D.
What is your price level? Sonoma Mission Inn is gorgeous. There are a number of B&Bs in Sonoma (one is right off Sonoma Square).
Sonoma wine country is actually pretty big and there are different areas. I am most familiar with the south part of the county.
Carneros is the area in the south. Gundlach Bundschu is a beautiful winery, but they charge for tasting.
Artesa winery is in Carneros, but I think it is actually Napa County (very close).
Gloria Ferrar produces great sparkling wine.
Cline and Viansa are wineries just north of Sears Point Raceway.
Cornerstone Gardens in Sonoma is worth a visit for the gardens and retail (Meadowcroft Winery has their tasting room there)
Schug is also fun and there is another winery close.
Sebastiani has historical tours (very old winery)
All of these are within 15 minutes of dowtown Sonoma.
And then there is the Russian River Area. More spread out, but fabulous scenery.
I would recommend sonoma.com. Plan to visit one area, especially if you are only there for a long weekend. Feel free to message me if you like.