Ed
I'm not bringing the wife to Miami. We have 2 kids so it's a nogo for her. We were fortuneate for Vegas to have her mother visit that week when she couldn't get the Christmas week off her work.
Best bet is to book a room soon. You can cancel rooms without any charges a few days before. Last year I waited too long and couldn't get a room and had to stay down the street. Only 6-7 min walk but when it's 90+degrees out, it sucks ass.
The Miami floor is smaller than Vegas but as we all know it's about the contacts you make.