Just learned that the (10) nights one is awarded for renting a conference room does not count as 'real' nights on your Marriott Rewards account. Weirder still is it counts toward your Silver/Gold/Platinum/PlatinumPlus status, but ONLY if it's not part of a promotion to achieve the status. Yeah, I know, really confusing.
I had a promotion that if I accumulated (20) nights by Dec 31, 2012, I would requalify for my Platinum status even though I'd be short of the (75) nights.
With the (10) nights added from my conference room reservation, I exceeded the (20) nights, but, learned Marriott Rewards did not count the (10) nights toward the (20) night promotion!
I emailed MR Customer Service that the terms & conditions of the (20) night promotion simply stated 'nights' only to be told, 'sorry, promo nights don't count'.