FYI: It is a bit unclear right now, but it appears that Marriott is running some form of Stay 2 nights get 1 Free for Marriott Rewards members starting on May 1.

The promotion is bare bones and does not state what properties qualify for the cert, nor when the cert could be used or even what are the properties where the cert can be redeemed.

However, I hope this is a harbinger of things to come among all the frequency programs!