My kids (4 and 5) are always excited to travel, and they're curious -- they want to walk around and look at stuff. If you have the option, I'd recommend walking them around the airport first, and pointing stuff out to them. It will satisfy their curiosity, and they'll also get some exercise and be much calmer for the rest of the wait. (They may be tickled by something as simple as riding in a skycap vehicle.) Then have them draw "travel photos" to mail to folks back home. It's creative, it keeps them occupied, and my parents love getting them.
Keeping the kids occupied