Hi Sarah!
My favorite time of year to go with my family to Walt Disney World is in December for Christmas. Taking the family during that time helps to make the season even more magical!
I understand your concern over crowds, and how you might be concerned over making the most of your holiday celebrations at the Disney Parks. One thing that has worked for my family is to go in the weeks leading into the actual Christmas holiday. There are a few advantages to this, because not only will you deal with fewer crowds, but you will still be able to see all the holiday decorations throughout the parks and resorts. The resorts have beautiful holiday decorations, worth seeing as some of the creations are breath taking. If you can find the time to resort hop, do so. In addition, I highly recommend attending one of
Mickey's Very Merry Christmas parties at Magic Kingdom for even more holiday festivities, and even a little snow on Main Street!
Another thing: if you visit between 11/28 and 12/16 of 2010, your visit will coincide with "value" season. That means your resort rates will be less than if you visited closer to the actual holiday.
Of all the visits my family makes to Disney World, this is my favorite time of year to go. Hopefully, your family will go and you will create fun memories, too. Come back to the Moms Panel if you need anymore help!