My experience - yest and tonight at Marriott Melville, Melville NY (Long Island). When I checked in - I asked about a Suite - it was a quick "nope - sorry none are available". She said well we do have you on the conc floor.
As a plat - I am guar. conc access - putting me on this floor (same rooms as all the rest) is more a convience to me - not a upgrade. Then the broadband doesn't work. Got it to work - checked online - sure enough: Junior Suites avail for $20 more/nt. Called the front desk - and told them about the net - and said: I didn't feel the warm and fuzzy welcome, she dismissed my suite request etc. He apologized and said he would find me another room and send someone up with a key.
Long story a bit shorter - got a new room. The night mgr called and asked about my problems, denied that she didn't have any suites and agreed with me 100% about the importance of Platinum guests etc. Unfortunatly, no suites on the 4th floor (only floor with HS internet). So I passed on the upgrade. She told me if I returned to call her personally to book the room. I asked for her to comp my two nights of internet access - she said absolutly.
So, you may not get an upgrade - but I agree that it always needs to be brought to hotel mgmt attention. If the manager is *the problem* - then you are kind of stuck. But often - the behavior is corrected, and genuine effort is made to satisfy. If you aren't happy with the service, ask for free internet, MR points, a free robe, free movies, etc. Better than invoking the Plat guar. and might make you happier than a "corner room" etc.
But I will say this: I am very disapointed hearing about the service that others are getting at SPG etc. Upgrades to Plat do include suites and should happen 50-75% of the time automatically. If it doesn't - I will go somewhere where 75+ nts a year mean something to me. $1 bottles of water I can get in the lounge - I want more comfort and service. I have another issue with the measly 30% bonus on MR pts for the Platinum level but I will address that in another issue.