Sathish:
What a memorable Christmas!
My first recommendation is to choose a resort that is near the theme parks you think you will most likely visit the most. My hunch is Magic Kingdom, and my recommendation typically for this age is
The Contemporary Resort. This will have many benefits during the holidays: 1) you'll be on the monorail and can keep the young ones strapped into their stroller from the park, to the monorail all the way to your room 2) if you experience bad weather, you won't have to go outside to get to your resort room. The monorail delivers you into its lobby 3) you'll be closer to the park for earlier entry, allowing you to leave after lunch when crowds get thick to enjoy a nap and 4) you can return to the park hassle-free in the evening.
Book your dining reservations ASAP. Christmas is a very busy time of year and you don't want to fight the crowds for a dinner seat. I'd book a
Character meal the night of your arrival so you won't feel like you have to stand in the long lines in the parks to get pictures with your favorite character. Avoid booking breakfast meals as that will be the best time to be in the parks to avoid the biggest crowds.
Lastly, don't be afraid to let the children to take extra-long naps. This may allow them to stay up later to enjoy the fireworks and the smaller crowds that you'll find in the parks after 10 p.m. If they turn into pumpkins before the fireworks, the Contemporary has some memorable theme-park-view-rooms from which you can see the fireworks.
Wishing y'all a magical vacation!
Whitney