Hi Joy,
You are visiting Walt Disney World during one of the best times of the year. As soon as the Thanksgiving crowds leave, you and your family should find that you will have lot of room in all the parks to enjoy the Christmas decorations and festivities, along with all the normal attractions.
I highly recommend
Mickey's Very Merry Christmas Party at Magic Kingdom, which will be held four times during your stay. It is a separate ticket event with limited admissions, and it is so much fun to see all the attractions and special parades and fireworks. I'm also a fan of the Candlelight Processional at Epcot and the .Family Spectacle of Dancing Lights at Hollywood Studios for holiday cheer.
Art of Animation is a great resort with some of the best themed decor in all of Walt Disney World. The Nemo suites are in the center of the resort and the Little Mermaid rooms are at one end. I would suggest your family ask to be on the Hourglass Lake end of building 5 and you request the Hourglass Lake end of building 7. Make sure you each note on your reservations that your are traveling together and want to be as near to each other as possible.
In my recent stay there, we were in the Cars area, in the building farthest from the center of the resort, and we found we could easily get to Animation Hall and the Big Blue Pool in less than a 5-minute walk.
Special requests aren't guaranteed, but I've always found that the resorts go out of their way to try to meet your needs.
I hope that is helpful. Please let me know if I can answer other questions for you as you plan your visit. Enjoy your time with your grandchildren!
Wilma