There are ten of us going this June. My suggestion would be to not try to spend all your time together. If some want to go off on their own don't get upset. We are not planning to do everything together. The only thing we will definetly do together is 1 character breakfast and on the days we go to the universal parks we will ride together. To many different ages to try to stick together.
I'm taking my neice and her family, my mother, my 17 year old son and a friend of his, DH, DS-10, and DD-3. My neice and mother don't want to eat out alot but that is what my immediate family likes to do. We have a 2 bed and studio so they can cook all the meals they want. I'm just providing the lodging for them.
I feel we will all need some down time from each other. It sure will be nice to spread out. Plus that onsite transportation will sure come in handy!
Have lots of fun.
Lori