Guess it's just random but all 3 stays after I hit 100 nights have been upgraded to a suite. This is after getting just a single suite upgrade all year. I'm also considering a Starwood challenge, mostly because I want access to cash and points for European vacations. I still plan to stick with Marriott for the most part. Marriott could do well to introduce suite upgrade certs that you earn after 100 nights or something to that effect.