One of the more useful items that I have found is the Gerber Spill Proof Water Spout- a nifty little blue top that pops onto almost any water Bottle (I use them in multiple countries!) and turns it into a kid friendly sippy cup. They are small, portable and Cheap- and take up a lot less space then your normal cups. They can leak some but it is a heck of a lot better than pouring the whole bottle on their lap during take off.....