Lived in AUH for a few years and did the trip back to Chicago about 3/4 times per year in addition to other countries. What worked best for me was to book my AUH-ORD legs via AA and get the credit to my AA status. I was then able to use BA and EY to fly to Europe, Italy, Etc either crediting thru my AA FF program or EY's. We really loved our time living in AUH and miss it often. Hope you have the same great experience!