The Hyatt in downtown Santa Rosa is in an excellent location from which to explore the Sonoma and Napa wineries. The rooms are large, quiet, and decently decorated. The breakfast restaurant is attached but you need to walk outside to reach it (as it appears to be run as an external restaurant).
The building is a rambling 3-story pseudo-Spanish style place. Outside restaurants and some wine-tasting places are within easy walking distance. I was pleasantly surprised to see the local and organic scene, which I did not expect in the historic district of Santa Rosa.
You will need a car or tour to sample the wineries... all within a comfortable distance.