Well see when you try to stick together, of course there are going to be problem. And if you're on the road, you're only stuck together for what, 2-3 days each way. Disney provides transportation all over the place, and in every way. I know, I just spent three days up there on disney transportation. (We went for the water park, and got rained out, and our seasonal passes aren't good till august 18th.)
In any case, who cares about sleeping habits? If you want to do a character dining, why not choose lunch, if you want to get all the kids together for a group photo. That way if one family doesn't normally eat breakfast, they don't have to.
And eating habits... Try doing something with the most pickest eater of all time. And generally a family style place would be good for any picky eater. Or just go over to the grocery store and pick up something that doesn't need heating. You can find anything there.
You don't plan the trip as a great wonderful time together... but more like "yay, we're going to Disney"... and we're gonna do our own thing.
I guess I see the one problem with foriegn travellers, you only get to make one trip down here every so many years... especially when you got kids in school. So you want to make the best possible trip for every one. Down here in Florida, you have a bad trip and you say, well we can go in a few months just by ourselves.
And generally if you invite a friend of your kids, and not the family, the kid will adapt to your schedule of eating, sleeping, and such. Plus if they gave thier kid like 500$ to spend on whatever, they'll sometimes be more willing to be "little things" for your kids if you say no. Like if you say no to a autograph book, they'll be like "I got money, I'll buy it for you".
Another option, if you can't get along wonderfully like the kids can. Get some two way radios, and let the kids have fun together (as long as they are of age), and you don't have to bother with the other parents and you can have a leisurly afternoon any where in the park.
There's a million ways to make it work. And you just have to let every person do thier own thing. And if you got grouchy grumpy people that dont want to be there. Then tell them, enjoy yourself, and we'll see you at the end of the trip. And if they really want to back out, tell them to hop on the Magical Express and get a plane ticket home.