Citibank treats the payment as a purchase, meaning that you'd get the usual mileage on payment. Whether paying, in essence, 2.5 cents per mile is worth it is really up to you.

There is a long-running thread on various bonuses being run by credit card companies with regard to paying taxes. I don't recall that the AA Citibank cards have been among them this year, but you might find a card that is worth considering for next year:

http://www.flyertalk.com/forum/showthread.php?t=527045

Mike