What I find interesting as a Plat Premier and occasionally staying at SPG properties as a mere Plat is that SPG properties almost always take a suite upgrade as a requirement. I never have to ask at an SPG property. At a Marriott property -- where I have a higher status -- I often have to ask.

That being said, my upgrade rates to suites are fairly comparable at both brands although I haven't been tracking (I'm switching back to focusing on Marriott properties now because I'm a little concerned about PP renewal -- not that it matters!)