You know you can go to any local furniture store and they will have covers that the couches and loveseat come in....most are covered with a big, heavy plastic bag, a lot of them being lined with a thin layer of closed cell foam.
They make GREAT bicycle/motorcycle motorized bicycle covers and are scratch free and water proof. If one were to fold under and tape the bottom edge with a piece of chain enclosed in the fold, they make REALLY GREAT outdoor covers.