They grossly oversell the 5K miles feature, and when flight attendants wake people up with the credit-card-pitch loudspeaker announcement, some of what they often say is flat-out wrong. The tickets aren't systemwide (you need more miles for longer distances), and the seasons for booking cover maybe a third of the year, including the spring and fall dips and when kids are in school.

I've found that availability changes and that seats often get added closer to the flight time. One thing I've noticed is that because of all the expansion in the U.S., the low-mileage credit-card award trips to international south-of-the-border destinations are a lot harder to get lately. Demand is higher because of serving more destinations with more flights, but supply internationally has grown much more slowly.