Hi Samantha,
What a great time of the year to visit the Walt Disney World Resorts! I love the holidays at WDW!
I the one thing you must do is not everything! With the crowds being so high, you will not be able to get to everything. When we toured during the week between Christmas and New Years, we each picked three things in each park we had to do and did those. Then everything else was a big bonus!
I will tell you to visit Epcot and experience Holidays around the World. Each country in the World Showcase will tell you how they celebrate the winter. Each is different and wonderful. I would also encourage you to see the Candlelight Processional. This is a wonderful telling of the birth of Jesus Christ. While I am not deeply religious, it is deeply moving.
You also need to head to Disney's Hollywood Studios and see the Osbourne Family Festival of Dancing Lights. One word-awesome!!!
Finally, you are going to need to eat and you will need to make Advance Dining Reservations. I encourage you to eat in as many resorts as possible. The resorts are so beautiful, and they still the show.
Have a magical vacation!
Beth