In November 2011, while changing planes in Denver, I was lured by a vendor offering to sign me up for a Southwest Airlines credit card. Southwest was celebrating their expansion in the Denver market by offering 50,000 “Rapid Reward” miles as a sign-up bonus. I had a few minutes to kill so I talked to the vendor about the offer. He convinced me of the value of these Southwest frequent flyer miles by mentioning that the miles could be used on any flight — there are no blackout dates on Southwest. The annual fee for the card, issued by Chase bank, was $69.