From The Points Guy: Seat assignments with miles on American Airlines. On some AA flights, it seems that all non-middle seats have a fee, and the extra-legroom Main Cabin Extra seats have a higher fee. They report that miles can be used for the fees at about 1.1 cents per mile, not a great use of miles but good if you consider them "orphan" miles that you don't see growing towards a useful award. All for whenever people think about flying again.