Spare room/craft room (or more accurate: my craft room with a bed so I never have to leave!) Article is actually about "thoughtful teenage bedrooms" but I see the room layouts as potential "studio-guest room combo.
"The living cube" I moved into a apartment studio without storage room. So i made a minimalistic cube design with a shelf for my vinyl collection, my TV, Clothes and Shoes. On the cube is a guest bed and inside the cube is a lot of storage space.