We went last Christmas. Our first MK day was December 23. We headed straight to 7DMT, following the crowd on the right side of the train station, which goes by the tea cups, and only had a 10 minute wait. After that, we rode Pooh, PP, Small World, and had a few minutes at the Tangled bathrooms. When the rest of the park opened at 8:00, we went to Haunted Mansion, Jingle Cruise, and PoC. The family was promised breakfast and coffee at Starbucks if they cooperated with my rope drop plan. By 9:30 we were eating breakfast at a little table outside the Plaza and then took a few minutes to gawk at the Xmas decorations on Main Street, watch the trolley show and take pictures in front of the castle. Then we went on 7DMT, Splash, BTMRR all with FP+, and managed to fit in Country Bears and Tom Sawyer Island between those rides. Lunch was at 12:30 at BOG. I was happy with how much we were able to accomplish.
The second MK day was December 27. We headed to Tomorrowland. Some of us rode Space Mountain twice, some rode Buzz three times, before we all met up again. Then we all went on Buzz another two times. I can't remember where we went after that. You can get a lot done at rope drop, even during Christmas week. The crowds started rolling in around 10:00.
If you don't want to ride the big rides, you should be able to get a lot of rides done. If your kids want to see Fantasyland first, which they probably do at their ages, I would head to Peter Pan first, then Pooh, and then whatever other rides they want to see.
We also managed to see A&E at 12:30 a.m. one evening, with only a 10 minute wait. The sign said it was a 30 minute wait, but we chanced it and were pleasantly surprised. Also, Talking Mickey and Tinkerbell had 10-15 minute waits around midnight. Your kids may not last that long, as they are young, but its an option if you don't have FP+ for those meet and greets.