Would stays at Starwood properties count towards the Marriott Platinum Challenge? Assume I’d need to use the Marriott Rewards number for the stays to count?
As far as I can tell a "Marriott Platinum Challenge" must be done at ... Marriott's
Currently there are no mechanisms for SPG points or nights to count directly to your Marriott account (can only transfer points), thus there is no way for them to track or count nights towards a challenge. Two different programs. You can of course call Marriott customer service and ask, as that is who you would initiate the status challenge with. But my solid guess is no. At least not until the programs are fully merged and everything runs through one single website / system / program.
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