We have visited Colonial Williamsburg (http://www.colonialwilliamsburg.org/) before, but not at Christmas season. Although Christmas decorations are not historically accurate to the time period, they do decorate the buildings, with the requirement being that materials used must have existed in the eighteenth century. Other than that, creativity can be exercised, although most look fairly traditional to our eyes.
Although a bit unseasonably cold, it was a nice time to visit, as it was not as crowded as summer, but was still surprisingly busy. It appears to be a tradition for many families to go there at holiday time.
We had two very nice meals in the colonial taverns, and dining (as well as getting around) with minimal lighting after dark certainly contributed to the eighteenth century ambiance.