As I always say to people who are going - no matter how much you try, you'll not fit EVERYTHING into two weeks. Just far too much to see and do and you'll end up hating it as you become more grumpy as the weeks go by, due to tiredness and stress.
You're better off peeking around the website for Disney World, Sea World, Universal etc and scribbling down things that are must-see's for you family and then things that maybe you'd like to do if there's time, followed by 'bonuses' if you happen to stumble across them.
That way, you know you'll fit in something for everyone and have a great time. As others have said, if you have little ones, you'll need some time out at the pool at the hotel/villa etc. Then again, even us adults need down-time, it can be a demanding holiday!
And don't forget, whatever you don't see this time, you'll see when you all return

'Coz I'm pretty sure that by the time you've all been and seen what you can on this trip, you'll be hungry for more!
Have a fantastic holiday!