Although kids need a lot of stuff, the more items you bring, the more things you have to lug around.
Over-prepared is best. Have extras, backup plans, and ensure the carry on has needed items
If you are traveling by plane, give yourself plenty of time to arrive at the airport before your flight leaves.
That doesn’t mean you need to only pick kid-centric activities, but you should choose kid-friendly attractions and activities to keep all members of the family happy.