Plenty of domestic airfare sales, with no end in sight, make this winter a good time to travel within the U.S. Affordability in the Napa Valley piggybacks on this trend, since a good deal on airfare to San Francisco or Oakland puts you just a car rental away. Savings on dining, spas, and lodging are the keys to an affordable Napa escape, and this winter, you'll be able to find all three.

January marks California's first statewide Restaurant Month, and participating towns in the Napa Valley include Calistoga, Napa, Rutherford, St. Helena, and Yountville. Offers vary by restaurant, but include, for instance, a three-course lunch at Bistro Jeanty for $55 a couple and a late-night three-course prix fixe meal at Bouchon Bistro for $25 a person.

At the north end of the Valley, Calistoga's quaint downtown will be abuzz in January during its Health and Wellness Month. Spas and hotels will be offering deals such as two complimentary mineral baths or signature Calistoga mud baths with a night's stay at participating properties.

Accommodations deals span the price spectrum this winter. For instance, at the budget Discovery Inn, a midweek winter special puts rates at $65 per night, and the Golden Haven Hot Springs has $75 rates that include a mud bath on certain dates in December. A midweek second-night-free offer at the boutique Maison Fleurie, or 50 percent off the third night at The Napa Inn bring down the cost of a more luxurious stay.

Looking to extend a Northern California vacation? Mendocino, about three hours north of Napa, is one of our top off-peak destinations this winter.