Welcome to the boards.
You are about to embark on a wonderful adventure.
In addition to the above mentioned excellent ideas, there are some basic principles you should keep in mind.
1. Even with 10 days, you are unlikely to see literally everything there is to offer. But with 10 days, even at this hectic season, and it will be getting hecticer and hecticer (not really words but you know what I mean), you will be able to see all the good stuff.
2. You MUST, absolutely take mid-day breaks. Even the adults. You may not feel as though you are getting your money's worth if you are back at the hotel, but it is absolutely vital that you take a break every day. I would suggest hitting the parks first thing in the morning and staying until just an hour or so after lunch, then head back to the hotel. You should plan to be in the hotel room or the pool if it's warm enough for at least 2 hours. You can then return for the evening, when all the people who didn't take a break are heading home. The breaks are essential to avoid what i call the 'check-off' mentality. ''Just two more rides, then we can leave tomorrowland." That's not fun, that's a project.
3. With a 10-day trip, you should also plan at least one and probably 2 days where you don't plan to go to a park. The hotels at Disney are fabulous if you are staying on site. Sleep late, enjoy a liesurely breakfast, swim, shop, look around, don't stand in line for a ride or show. Go to bed early and be refreshed for a new assault on the parks.
4. Get copies of all the park maps on your day of arrival and plan the things that are must sees and the things that are 'if-we-have time." While I don't suggest sticking rigidedly to a plan, it is a good idea to have the first several attractions of each day planned. This allows you to make better choices for the rest of the day based on lines, location, desires, etc.
5. Use the Fast Pass system as you can. This will become increasingly important as you get closer to Christmas and the crowds build.
6. See the holiday shows. They are superb.
7. Enjoy the moments. You are at the world's largest enterprise that is designed for your enjoyment, particularly the young travelers. These people are very good at what they do.
8. With this large a group, not everyone is going to want to do everything. That's okay. Just plan when and where to meet up.