I did have a thought about the blue room and the peeps smelling it from the doorway. One of the notes from Margaret says that the room is to be big enough for 3 little boys. Now as the room was never finished, we know that something stopped Margaret and Bill from finishing it, Bill's death perhaps? My thought was that what the peeps are smelling might be Margaret's perfume. (Yes, ghost are reported to leave smells) If Bill had died, and with his death her hopes of having children, can't you imagine Margaret standing in that doorway, mourning not only Bill, but her chances of having all those children, too?