Say you have a kid at that certain age, who just wants to be left alone to read her book and listen to her iPod. Congratulations! You've got a voracious reader on your hands. But in the thick of things, when you're already stressed out about life on the road, it can be maddening to see your child opting out of this great gift you've given her.
Likewise, trying to plan around kids of varying ages can be its own minefield. If your oldest loves museums but your youngest gets bored easily, you're looking at a fairly annoying situation if you haven't balanced out those facts.
That's why it's important to make sure that every member of the team has a stake in the trip as a whole. Sometimes a little downtime -- even splitting into teams for an afternoon -- is not only necessary, but can make your kids feel even more special and loved.
By involving the whole family in these decisions -- from where to go and what to see, to when it's time to get out and stretch their legs -- you ensure that everybody feels ownership of the trip. It'll solve more arguments than you might think.