A plain sofa is not a problem until you actually sit in the room with it. Then you notice it. The flat cushions, the single color, the way it looks functional rather than lived in. A duvet set thrown over the back of a sofa or folded across the seat is one of the oldest tricks in the book and also one of the most effective. It adds texture, warmth, a sense that someone made choices in this room rather than just filling it. What we have found is that the wrong one makes this worse, not better. Something too thin, too shiny, or in a pattern that fights the room does real damage. We have been looking specifically for duvet sets with the kind of weight and surface interest that do actual visual work, in colors that settle rather than shout. These are the ones that make a sofa look like it was always meant to feel that way.