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.
IKEA Hemnes day bed: Sofa by day and bed at night, most of our comfy day beds even have built-in drawers to store duvets and pillows. Many can turn into both single and double beds and you have a choice of mattress to get the comfort you prefer.