I am new to being a member of this forum but I have been following you all for years and I don't want you to think this is another "why wasn't I upgraded" post. Marriott has actually been fantastic to me in terms of upgrades; suites and otherwise, so I have zero complaints there.
One thing that has left me scratching my head over the years, however, is what criteria is used when assigning rooms at check-in. I do the majority (70%) of my business related travel with a co-worker who is a Gold Elite member (I am Titanium Elite). I would say that I am clearly upgraded to a high floor corner room or a suite about 50% of the time and that is an excellent percentage so that isn't the issue at all. I am just curious about the times that doesn't happen. If I am not given a clear upgrade, my co-worker consistently gets a significantly better room even though we are checking in back-to-back. Say it is a typical middle of the hallway room, I will be on the 20th floor and he will be on the 30th... it seems strange to me.
My co-worker is a guy that bounces around hotel chains and achieves lowest-tier status at as many hotel brands as possible. My travel is 100% with Marriott because I enjoy the perks of the top tier at a single company and, since I only travel just enough to get Titanium with Marriott, I have no desire to spread it around. When I get the suite and he comes to check it out, he always says "maybe I should just focus on top tier in one brand" but when we have identical rooms and he is 10-15 floors above me, it seems to reinforce his belief that mid-tier in multiple chains is preferable.