Originally Posted by
DrivingRain
Yes, exclusivity and the $$$ that came with it ruled these choices.
AA=Citi
UA=Chase
DL=Amex
Some lingered for a little bit until the out-clauses came along (ie AA and AXP). It's now a blood-sport. It's why you see a Cent lounge in the middle of the AA operation at MIA-- to keep/get-back Citi users, same with SFO vs Chase, similar with IAH (AXP would have wanted to be closer to UA, but they're just happy to be there). It's not the only thing driving their strategy, but it's a decent part of it.
I'm surprised the Skyclubs stopped allowing guesting on the Plat card with their close relationship with Am Ex. As a Skyclub member I think that is one of the best choices the SC Made though, the lounges were too crowded before and still are sometimes at peak times. When Delta introduced the executive membership they probably had to make the change as well seeing a Plat and reserve fees are less than the Plat Am Ex Annual Fee.
And it makes sense that Hyatt would continue to issue the day passes to the United Club since Chase handles both their cards.
I noticed Am Ex offers better benefits to Delta card holders than Citi and Chase does to AA and United cardholders. I believe there is a cap of like 10K elite qualifying miles with AA and United on credit cards where I will earn 100K MQMs with my Delta Am Ex cards this year. With Delta the $25K credit card spend MQD waiver applies to all levels and I know with United the waiver doesn't apply to 1K.