Here's an absolutely brilliant tip for traveling with young children from Parent Hacks:

When we go to crazy places like amusement parks and fairs, we just use a Sharpieand write on the kids' stomachs "My mom's cell # is...." The kids areall drilled on what to do if they get lost, and we have photos of themat Disneyland and everywhere else, flashing their bellies with theemergency plan.