There is a rumor on FT that Hilton’s Q1 promo is going to be; Earn 1 Free Night Certificate at any Hilton for every 4 stays or every 10 nights at participating Hilton Hotels. See the chatter in this FT thread. The word is that every Hilton Hotel has automatically opted into the promotion.
This promo has potential depending on the free night certificate restrictions. Even though Hilton is planning a devaluation on January 15th, this promotion may still be worth the look. The rumor is that the new top tier will be more than the 40k Hilton points that is currently required. It may make sense to leverage the 4 stay requirement to earn multiple free night certificates (several 1 nights stays in a week), which would be a bonus of more than 10k per night.