Guest room- Create a nook like this by suspending curtain rods from the ceiling. Put a daybed to be the bed in a small bedroom. Closing curtains allows you privacy to maximize all space for lounge and storage- its ok to have chairs right up to the bed!
Great idea RE the twin mattresses. I also love the tree pictures on the wall! Love to display kid-made art in a kids room! Two twin mattresses, some plywood, and a great playroom that doubles as a guest room or sleepover room.