Definitely get them involved in the planning. Also try to set aside time for yourselves to things on your own.
I totally agree with everyone on checking out the menus on Allears. I had the kids do that. We also decided that everyone would pick a restaurant, that gave us 6 of 10 day vacation meals.
You are most likely going to want to try to show then everything so have them write a must see list and work around it. You know what goes into seeing the world and try to plan your trip in the way they would be on vacation. The worst thing is to try to go commando on someone who has never seen the world. Show them the best time you can without overwhelming them to the point they become dizzy.
Enjoy planning your trip.