Do not loose any of the goodies you get by flying – make sure both you and your kids subscribes to the airline program. I like to to this before I fly, since I know it is stressful enough to remember it at the check-in.
This year, me and my kids only payed roughly 1500 dollars for our flight, since we could use our rewards to buy two of our tickets. You see, you can still use your reward points towards a new flight, even though it is not totally enough. And if you only have a few rewards points, then you can use them for something else, like getting a subscription on a Magazine. Check the web page of the company you are flying with.
Now, that is sweet!