I belong to BA because of the Diners transfer opportunities and the opportunity to use awards on AA domestic and to upgrade AS. AS RT upgrade is 15000 BA miles which on first blush seems expensive unless as a result of Diner's xfr then it is 7500 miles or a savings of 2500 from AS upgrades. I believe that this may be the only program that allows use of miles to upgrade another airline. NW & CO do not count in my estimation.