As a Platinum, I've gotten upgrades and other assists about 75-80% of the time, usually without even asking. The Marriott in FLL is excellent - upgrades to high floors, marina views, junior and full suites, and a gift pack every time - and this even on a negotiated rate my client has there, much lower than the usual rates. At Courtyards, sometimes upgrades to suites, although not every time. One thing I've been pleasantly surprised by is Marriott's policy of upgrading free stays - at both the Renaissance Manchester (UK) and Vancouver, I was put on the club floor despite being on a totally free certificate stay. In fact, at both places they seemed to take it as a complement that I had decided to "spend" my points there. Very different from how the airlines sometimes treat us when we're flying for "free".