I like the little day bed and the window and beat board walls. day bed on plywood base with built in table. we would put the long edge further back for under the bed storage space. I also would want to paint it like white or something.
You don't need no stinkin' sofa! Put some nice fluffy cushions directly on the floor. Take that futon cushion off the frame and fold it against a wall. Add pillows and blankets. The options are endless!