Christmas at Disney is such a fun experience! It's great that your children are into it.
Here's a great idea from the past. It's a little trickier now, but still fun.
Set a dollar limit (say $5 per) and visit each country in the world showcase. Purchase something within those limits and fill their stockings. It's a GREAT way to enjoy Christmas morning, especially if you have them guess which country each little giftie came from.
We are going to be doing it again this year. :D (You do know we're going to Disney for Christmas too, yes)?