It's not a 'promotion', but part of the Platinum benefits.

https://www.marriott.com/rewards/mem...ts/platinum.mi

"Weekend Discount
Enjoy a 10% discount on regular rates for your Friday and Saturday night stays at participating Courtyard® and SpringHill Suites® locations."

The question is do they mean rack rate when they say regular rates? In which case, weekend rates might be better. If it's 10% off regular weekend rates, then it could be a good deal.

Cheers.