We're flying across the country in a couple of weeks with our 3 and 4 year old girls. It will be their first time on an airplane which is exciting, but one of our legs will be 4 hours long! Any tips for activities to help keep them occupied on such a long flight? We will be bringing our portable DVD player (w/headphones) as well as crayons/coloring books. But was wondering if anyone had any other great ideas to share that may not be so obvious. (We'll have a 2-hour layover too and then another flight - ugh - yes, we're crazy!) TIA!