I'm bumping this up to the top of the blog roll as a reminder to make a change by TODAY. You must choose the designated airline for any Platinum card (including the Business Platinum), and the Hilton Aspire card (which comes with up to $250 incidental fee credit) by today as well if you want it to be different than last year's. 

One of the most valuable benefits of the Platinum Card® from American Express is up to $200 in statement credits for incidental fees with your designated qualifying airline every calendar year.