Another vote for Central and So. Cal. My favorite area south of Big Sur would be the Central Coast. Cambria is a cute beach town and you could do wine tasting in Paso Robles. San Luis Obispo is nice and of course there is Santa Barbara. More wine tasting in Santa Ynez Valley. But weather in January could be iffy as others have mentioned. So as much as I love the Central Coast, you might be better off in San Diego/Orange County. At least if we get a lot of rain, there are more of a variety of indoor activities.

If you want to fly into LA instead of San Diego, you could play it by ear. If the weather is nice head to Santa Barbara, if it's cold and rainy there is plenty to do in LA or you can head down to Orange County. Laguna Beach is beautiful. There usually isn't much problem getting a hotel room at the last minute in January especially in beach areas.