For various reasons our whole family was not able to sit together on the plane for our flight to Europe. So, I got the boys in the back and my husband got the baby in the extra leg room section. Since he’s tall I figured he could deal with the toddler who won’t sleep. Although it turns out we both got the shaft in that arena, since the boys were so excited that they had their own televisions and headphones they watched Toy Story 2 all the way to Europe.
Anyway, my point is there is a lot to be said for everyone having their own carry-on while flying. It may seem more efficient to combine things into one bag, but in the end you spend more time rooting through that gigantic bag than if you just carried a few smaller bags. And for us, it was easier to separate when it came time to do so on the plane.
If you don’t want to go that route, at least use packing cubes or smaller pouches inside of the larger bag. Color code or label each person’s pouch so it can be easily found when the baby needs a diaper or the older boy wants his book.
Finally, if your kids are like mine, they won’t use half the toys you pack, so after you pack, go through again and streamline. If you are on a long flight, there will be a movie. If it is an evening flight, they will hopefully sleep. And there are always snacks.