Well, I think you answered your own question. "They have very consistent properties across all brands... and they seem to be everywhere." For someone like me who never uses points for free nights, lack of award night availability is not a problem. Marriott's consistently excellent product, far superior as a general rule to any other brand, makes them the clear winner for my hard-earned money.

Also, Marriott has made some great strides in the high-end hotel and resort arena lately. In quite a few locations they now give St. Regis and The Luxury Collection a run for their money. I'm not telling you not to stick with what works for you, but trying to explain why Marriott works for me!