We made our first family pilgrimage to the house of mouse December 4th-13th of '04.
I can tell you we had an absolutley fabulous time. Great time of year to visit. X-mas is in the air and lines are non-existant! Our kids are 9,8 & 5. They loved it. So did we!
We loved it so much we are now DVC members.... we will be visiting the mouse every year!
One of the best tips I got (from here) was to take hats & gloves for the kids (and adults too). We bought Mickey winter hats & matching gloves at wal-mart for less than $6 each. They were wonderful. Only needed them for a couple of nights, but we were able to continue enjoying the parks when many others were leaving.
Have fun!