And the times I stayed at the Mayflower I got a crummy, worn-out, tiny standard room. Upgrades certainly vary, but officially all you're entitled to is access to the concierge lounge (if a property has one and it is open). In reality, plats get a much better upgrade rate to the actual concierge level, corner rooms, larger executive rooms, junior suites, etc. In my experience, though, Marriott properties simply don't have that many full suites and they are generally booked by paying customers or given to conference attendees who book tons of rooms at a time.