If you are planning on using frequent flier miles, or some equivalent "freebie" program, book your airline reservations as soon as you have accumulated sufficient points/miles/whatever. My DH kept telling me, "I fly all the time, you don't have to call 11 months in advance." Well, when he finally did call, 6 months in advance, all the "free" seats were reserved. The airlines only keep a certain number of free seats available. The plane has plenty of fare-paying seats available, but no freebies. We had to change our vacation date, and all the associated reservations (hotels, rental car, PS, etc.). It was a hassle. He's is only 1/2 way in the doghouse though because we will have to go sooner now.