I've been Starwood Plat for 4 years and Marriot since last year. When I first began staying at Starwoods, I would always have to ask the front desk manager directly for an upgrade and this did not always work (3 years ago). For the last 2 years, I have consistently been upgraded to a junior suite, whether staying at a luxury collection in South America or Europe or a Westin or W Hotel in the states. They have made a consistent effort to make Plats feel very special. I hate to admit it but my stays at Marriott have been the opposite. I can count the number of times I have been upgraded on one hand.