I received the following targeted promo via e-mail from Citi today.

Earn

2X AMERICAN AIRLINES AADVANTAGE® MILES on eligible purchases through 06/30/15¹

or

use Citi® cards with Apple Pay™ to earn 10X AMERICAN AIRLINES AADVANTAGE® MILES on eligible purchases through 06/30/15.

Respond by 05/31/15.

There is a 2500 limit on bonus miles. The fine print suggests that regular purchases are simple +1 bonus mile, and Apple Pay are a simple +9 bonus mile, meaning that there's a $2500 limit for regular and a $277.77 limit for Apple Pay. If you register you do not have to choose between them, and so it seems they can be combined (up to that 2500 bonus mile limit).

Eligible purchases for me included the categories Dining, Shopping, Groceries and Travel, which is a pretty wide net. This seems definitely worth it for the Apple Pay purchases.