You should try to take her Greystone - the Napa Valley Culinary Institute of America's Restaurant. It is in the north part of Napa after you have passed all the big name wineries. Great food, great services and it has a demostration kitchen - meaning you can see your food being made. However, it is a little pricey.
If you're in the mood to leave name there is Spenger's in Berkeley. They are owned by the people who own McCormick & Schmick's. In addition, they used to have a Monday Night $14.95 lobster special. Service sometimes suck but the best Cioppino and margaritas (fresh squeezed citrus).
If you want to go all the way down to Monterey there is a restaurant on the water called Fish Hopper. Award winning clam chowder. I go there everytime I'm close to Monterey.
Keep in mind that San Francisco is about 1 hour Southwest of Napa and there are a ton of choices there.