Hi
Very impressive you are starting the planning at least 1 1/2 years before the schedules will be available!
Based on my past experiences( I'm also the person typically making group travel arrangements for our family and friends vacations) the most important part is nailing down the dates!
It is more important than deciding on the ship!!!
With so many people and kids and ages in school it is important you can get a consensus early on!
People with young kids might not have much if an issue missing some school days but teens and High schoolers it might not be an option.
Once you have your "week" set up then you go for potential cruise options Dream/Fantasy/Magic/Wonder!
At this point is very advantageous to have a travel agent that knows
DCL!
There is a lot of peace of mind when you have this agent that is responsible for the deposits, final payments,dining linking etc.
I would say If you need one activity you do together it should be dinning!
At least have everyone agree in late or early dining!
This way if you decide on doing shows or activities as a family you will all be in the same schedule!
Tours definitely should be individual choice.
The only thing we did was couple tours we decided to let people ahead of time what we were doing and if anybody wanted to join they could book!
Example:
We did castaway Rays at a specific time 3:00pm
Also part of the group went together to Atlantis water park.
Another subgroup booked a bottom fishing tour together!
We did seat in the same general area in
Castaway Cay!
Regarding adult dining. Palo and Remi do have large(12) people rooms you can actually reserve! So it might be a nice outing one night!
So once you have a date selected the rest is Gravy!!!!
Good luck !