This is the weak point about Marriott - you can always ask for an upgrade - as long as you don't expect to get one, then you won't get disappointed. I don't ask for it unless we are travelling with the kids.

I talked to several FDC in Europe/Asia, upgrades are straightly one category - Plat got them before the Gold. If you want to go beyond that you need to get a hold of the GM or director of rooms.

1 category upgrade is still better than no upgrade in US FS Marriotts.