I've been told by a previous CM, do not do online check in if you have a room or location request. It's not that you won't get it or they don't look at your request but the rooms are assigned by a computer program and once assigned, very difficult to change as there isn't shuffling like when you are checked in at the front. It's all up to the computer and the actual ressie is handled differently in terms of catorgorizing rooms. I will say the people in front of us at our last trip had done O/L check-in and wanted a different room assignment. The CM said he would see what he could do, looked at their packed and said "oh you did on line check in. I can't change that, there are no other rooms available to switch to". Not saying it's set in stone, just seemed to follow what I've heard. Hope you get what you're hoping for.