I'm platinum at Starwood and usually stay at Starwood hotels, but some recent travels have had me at a bunch of Marriott brand hotels. I'm a consultant and travel every week so I'm pretty familiar with status matches and challenges. Starwood's platinum challenge will let you back date the start of a challenge within reason (i.e. if it's currently May, they would let me make the challenge start April 1, to include past stays). I asked if Marriott would do the same, and was told no. I was also told that there is no Platinum Challenge, rather only a gold challenge, and that I would have to have 6 different stays, rather than a number of nights. Is this truly the case? Has anyone else had the same experience? If so, I am seriously disappointed in Marriott and will be taking my business exclusively to Starwood from now on.