The back or

If a double sofa is planned, then there should be enough space on it so that both people can fit on it and not interfere with each other. It also matters the height of the sofa: having problems with the back or legs, or to an elderly person, it will be difficult to get up from a low sofa, and a small child will be problematic to climb on a very high bed on his own. Further — the sleeping place of the correct sofa should be even, without height drops and distortions.