This promo is worth approx. 10000 extra points after 20 nights.
The current Marriott one I was offered is 35000 after 25 nights.
About the same - works out to approx. double the base points.

I am just glad the SPG one starts Jan 5 (Marriott starts Feb)
Therefore, I'm not complaining. I will hit the 20 nights by the time the Marriott one kicks in, but this promo still gives double points after the 20 nights 4000 point bonus is achieved and I would rather get double SPG points than double Marriott.

Don't know if any other chain is offering anything better.