This is the perfect place to put a pull out bed. I always look at those beds and think they're impractical because it's too hard to leave all of the open floor space needed for one but I'd happily do it for this library/reading space
Book Nook in a fireplace that is no longer usable. Very creative use of space. Just make sure to clean that fireplace well before putting any books in there and to seal things to prevent water damage or pests from coming down the chimney.
6 Pane Window for master west side wall centered & South side dining room wall & South side wall in my office & remove single window on the south side wall. Remove both windows in Ryan's office on the South side and put this 6 pane window too