I am Gold, and I have never gotten a suite upgrade. (I've received a wonderful five-room suite as part of a large catered event, but never a two-room suite as a result of a simple paid stay with Gold status.)

Fortunately, Marriott rarely if ever messes up bed/smoking type, so I don't complain. Usually, I get a room on the concierge level, although it seems like Marriott lounges are never open.

My only minor complaint about Marriott: it seems like they NEVER want to allow a late checkout. The stock reply is "Sorry, we're sold out tonight." Since the answer is the same - every time - I have a hard time believing that.