Flyertalk Benefits
I would say:
(1) The fact that one may have up to 4 personal and 4 business UA VISA credit cards.
(2) The ability to get a cash refund on AA if an international nonrefundable fare becomes available for less than one paid (actual savings in 2004 for me was $170).
(3) The status match concept.
As an infrequent flyer, I would not have known about these items but for FT.