We would usually go to Disneyland in Paris every December when the schools here in Belgium broke for the holidays. Unfortunately this doesn't happen anymore since my daughter is away at university in Wales now. The past two years however, we went in January. The Christmas decorations were down last week when we went but most of the people were gone too. It was great to be there again and although it was cold, there were very short lines for the rides, which makes it less stressful and more enjoyable.
If you're heading to Paris in the next month or so, catch the train to Disneyland for a nice relaxing time. The park is very compact so you can see it all in one day. They also have the Disney Studios, which might take an extra day to enjoy. The train stops right at the park!