Originally Posted by pinniped

IME, suite upgrades are more common at Starwood than Marriott. I have far more lifetime stays as a Marriott Plat, but I've probably received more true suite upgrades at Starwood.

Marriott Plat has some important advantages vs. Starwood Plat, but the suite advantage goes to Starwood. Reading both boards here, I think most people tend to agree with that.