Hilton HHonors members can choose to earn double points or miles for stays through March 31, 2013. Registration is required at www.hiltonhhonors.com/Q12013 and once you choose to earn bonus points or miles when you register for the promotion, you cannot change your earning preference. There is also a lengthy list of non-participating hotels that you can find at http://insideflyerus.wpengine.com/link/?8031