AMS is a formal crew base. With FedEx closing the CGN base, don't know of any other U.S. carriers that have a formal base in Europe. WGA may be lacking a lot of things, but if you live in Europe, particularly in Northwest Europe, a short commute to AMS, versus having to rely on jumpseating or buying tickets to the States, goes a long way to towards reducing stress, increasing time off at home, and bettering QOL.