Traveling families typically arrive several hours before the flight is due to depart.  If your kids are like mine, the anticipation of the flight combined with having to wait for a couple of hours is a recipe for disaster.  Fortunately, a little planning can make this time fun and, more importantly, exhausting for the kids.
 
The excitement of arriving at the airport is immediately tempered by waiting in line at the ticket counter and security.  Halt the fidgeting and fussing with a surprise.  Pack a quart-sized ziptop bag with stickers, a notebook, a few crayons, a mini-activity pad, a car, a small tape measure, tissues and wipes -- you get the idea.  It will keep the kids entertained for a few minutes and start the trip off on the right foot. 
 
Once you have cleared security, it is time to burn some energy.  Most airports are exciting for kids with lots of energy -- interesting stores, interactive displays, etc. -- use this to your advantage.  Assuming you have plenty of time, wander through the airport in the general direction of your gate and let them explore.  Our kids once spent 30 minutes playing with a credit card display -- they systematically took every application out and put it back in a different spot.  You never know what might interest them.  Find an airport map and let the kids figure out where to go.  Play counting games -- count the airplanes found inside the terminal or count the number of people wearing hats. 
 
As you are walking, be on the lookout for an empty gate and stop for a while.  Now is the perfect time to play some active games.  Set the ground rules and boundaries, and remember to watch for out for other people -- the idea is to have fun but keep things under control!  The steps game is a fun one to try -- everyone comes up with fun steps.  Walk like a giant or a fairy, walk backwards, walk sideways -- be creative and let everyone make suggestions.  If the chairs are in rows, they can zig-zag between the rows and touch every chair.  A simple game of freeze tag also works well if there is plenty of space.  
 
Be sure to arrive at the boarding gate with plenty of time for last minute potty breaks.  Pull out the ziptop bag from earlier and begin the process of calming everyone down before boarding.