The holiday season (which begins at WDW in November and goes through a few days after new year's, usually), is beautiful. The decorations in the resorts especially are truly amazing (esp. the life size gingerbread house at the Grand Floridian!). We really enjoyed our early-mid December trip in 2007 because we had all the holiday decorations with none of the holiday crowds.
If we had to choose going with the actual Christmas week crowds in order to experience the holidays, though, we just wouldn't go. This was Liberty Square on Christmas Day 2015 at 9:18am:
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As much as I love the decorations and feel of WDW at the holidays, it's not worth it to deal with these kinds of crowds.