I spread my spending across 3 cards to maximize my point earning: I try to put Airfare and Amex-booked hotels on the Platinum (5X), dining on the Gold (4X), and everything else on the Everyday Preferred (1.5x if 30+ transactions per billing cycle, which I have no trouble meeting).
Across those three, I average somewhere in the ballpark of $100K/year in spend. No idea where that falls on the distribution though.