In our experience lightly staged rooms look best.  If you already have a tour room that you use for student tours we would recommend using that.  If you plan to decorate the room we recommend keeping it simple.  Here are a few easy items you can consider for the rooms.
Blanket & pillow with school logo/colors
School t-shirt or sweatshirt for closets
School notebooks or binders for the desks
School Banner or Flag