Platinum with mgm, as in Mlife?
If so, I would stay at sls as plat spg.
Spg plat is geared towards accommodations etc. Mlife is geared towards gambling.
Yes, Hyatt Diamond can match to Mlife platinum, highest besides the invite-only Noir. I have never stayed at any of the MGM resorts so I don't know much about the Mlife program other than what I read online.
We would be focused on pool/club/accommodations, less about the gambling.