Sleeping nook with reclaimed windows as doors. I deeply love this - I've always found the cubby/fort/hideout space very comforting. I like bunk beds, the bottom bunk, because they give one a sense of that. Though as a 6'3" adult, sleeping in the bottom bunk is not all that doable. Twice I've lived with my bed in a closet - this is just a much classier version of that.
this could have gone in "home library love", but this area is so much more than that. the abundance of white, the beautiful wood, the curving staircase, the awesome loft/nook filled with books. (audible sigh)