I have sensed that SPG offers less benefits when the stay is an award stay or a good rate for that property -- especially when compared to the standard company weekday rates. Sure the Starwood hotels seem to upgrade you, but rarely to the truly best available room upon check-in. It seems more like a pre-arrival or on arrival upgrade to satisfice, defined as a minimum level to reach a satisfaction threshold, instead of fully satisfying the intent of the program as stipulated in marketing materials related to SPG benefits of being Platinum.
In my last 20 stays as a Platinum I have gotten a suite 2 times .... and only once was it granted without inquiry -- Sheraton Grande Sukhumvit. The other time -- W Sydney -- it was a call back to the front desk saying my admin tells me you have a bunch of suites available and I thought it was an SPG plat benefit to get the best available room, suites included.
Ironically, at Hyatt where suite upgrades are not mentioned as a Diamond benefit, I have gotten suites 3 out of my last 16 stays -- all without inquiry.
If you are going to be wanting more high end properties in the more exotic of locations, then Hyatt may not meet your needs.
If I had to start shedding status, I would choose to be just Hyatt Diamond (for ever). I would remain Hilton HHonors Diamond (long enough to burn through a million HHonors points) and SPG Gold (long enough for those rare, vacation-only instances where I need 4 p.m. checkout or to burn through my 320,000 SPG points).