Active one would have to be the Hilton 50k.

I expect when this is done by staying only four nights to earn enough points to be able to stay free for 12 nights. I plan to do this by redeeming the points when point stretchers are available for the hotel I am interested in. In researching this, I discovered it will not be until October, but I spend three nights a week in a motel every week anyway, so October is no problem.