Registration is now open for Hilton's Double your HHonors promotion. Between March 1 and May 31, 2015, earn double base HHonors points or double partner airline miles on paid stays at participating properties (the list of non-participating properties isn't yet available).
To take advantage of this promotion, you'll want to select "Points and Points" as your earning style if you choose double base HHonors points, or "Points and Miles" if you select double airline miles.
I don't have any paid Hilton stays planned during the promotional period, but I registered and selected double HHonors points in case something comes up in the next few months.
In any case, register now, before you forget, and find the list of non-participating properties here (once it becomes available).
As always, you can always find my most up-to-date list of promotions on my dedicated hotel promotions page.