Best to peruse recent threads and then check back with more specific questions. Here are some starters:
Yes, a little more detail, please. How long are you staying? WHERE are you staying? Are you just into wine, or the food as well, and which is more important to you? What kind of wine/food do you like now? What DON'T you like (which is probably more important)?
Everybody likes to help, but out here details are everything; there is too much to do when you are time-constrained.
If you're lucky you'll have nice weather; if not it will be cold, rainy, and unpleasant (it's not fun driving on windy unfamiliar roads in the rain, LOL). But service will be good, because there aren't a lot of visitors and staffers will be more relaxed and spend time with you.
I'm thinking you are going to be asked for a bit more info.Like what you like to eat, how much time you have, and how much you want to spend, In December it MIGHT rain a lot; so far we have had some early rain, which is a good thing. Less fires, and if there are floods you can maybe get a seat at French Laundry. Especially if there is a mud slide. But that's usually not until January.;)
It's never really "rest of the US cold".
I live nearby,and don't have much experience with where to stay, but my current favorite is Farmstead. We also like Goose and Gander, Market, Press, and Mustard's when we are entertaining out of town guests. And Oxbow market.
You might do a "wine country", or "Napa Valley" search.