We plan for extended family too, and find that if one person makes the outline and plans the meals, no matter how many or few, it goes more smoothly than everyone planning their trips and then trying to mesh the plans together.
I think 'Ohana would be a good choice. It is family style so your group wil not be up and down all through the meal. You will probably need to have help booking it though due to the size of your party. Pick the day and time frame and both of you get online at 6AM at 180 days out and you will be fine.
For breakfast I would suggest a character meal in a park. WHat a fun way to kick off a day! We like Crystal Palace in the MK, and while it is not a favorite of mine, you may like Tusker House in DAK. For Epcot, I think Garden Grill woudl be a blast. That one is my favorite, and features CHip and Dale, with the food brought to you family style, like 'Ohana.
Another idea for a large group is Biergarten in Epcot. I bet that one would be fun for all of you.
I also know that Chef Mickey does not get much love here on the boards, however we generally take first timers there for an arrival dinner. There is something magical about pulling into the Contemporary on the monorail and heading to meat Chef Mickey and the gang. It is buffet, so it is what it is, but I like it.