To the left of the counter, at the back of Madame Malkin's, is a curtained-off doorway leading to a large room. Or, it would be a large room if it hadn't been mostly partitioned off into a multitude of smaller rooms, separated by walls and bearing their own small curtained doorways. Either way, there has to be an enlarging charm placed on the room, as the outside appearance of the shop wouldn't indicate the existence of this space. These are the changing rooms, for customers to try on their robe selections before purchasing, and each one contains a chair and a full-length mirror for people who would rather maintain their privacy.
In the area that is free of changing rooms, but still behind the curtain leading back to the main room, several comfortable-looking upholstered chairs sit, along with a three-way mirror against the far wall of the area for people to examine their robes in. If you are waiting for someone to try things on, feel free to take a seat and relax, converse with others, whatever you'd like (within reason, of course.)