Hi Karen,
Ooh...I LOVE planning
vacations to the Walt Disney World Resort during the Christmas season. My very favorite place somehow becomes even more magical as the decorations, music, and even costumes celebrate the spirit of the season! I think you'll find those two weeks to be pretty similar in regards to crowd size, with perhaps the first week in December having slightly lower crowds. I don't think the difference will be substantial, however, so I'd encourage you to plan for whatever works best for your calendar.
You're definitely on the right track with some of the must-do Christmas experiences! The Resorts are all decorated so beautifully! Be sure to visit Disney's Grand Floridian Resort & Spa to see the gingerbread house! Also, my family loved the gingerbread carousel at Disney's Beach Club Resort last November because there were hidden Mickeys throughout it. We stood there for probably 30 minutes enjoying the beauty of the creation AND the challenge of the hunt.
Candlelight Processional at Epcot was my number one item on my Disney bucket list, and it exceeded all of my expectations when I finally got to see it last December. Between the gorgeous music and the inspiring story, I had goose bumps through much of it and was even brought to tears. You're going to LOVE it! And of course,
Mickey's Very Merry Christmas Party with the complimentary snacks, snow on Main Street U.S.A., low wait times for attractions, Once Upon a Christmastime Parade, and special Character meet and greets is always an absolute blast!
Enjoy every moment of Christmas joy during your visit next holiday season, Karen!
Missy