I don't think the "random" comment is accurate. It seems they try to accommodate requests if they can, so if you have a request, when a human looks at it and is in a reasonably good mood, they'll try to work through it. Checking in early would give you more of a chance in case they pre-assigned a room to you and you happened not to like it and others hadn't checked in. I guess the main question is, is there any way to have your request evaluated for room assignment before others? Is there a day on which the rooms are assigned, and if so, is there any way to have them manually evaluate and make assignments even the day before that?