This is a perfect combo of my two favorite ideas for that space under the stairs leading to the basement. A reading nook AND book storage and shelves . assuming that there is enough space for this there.
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!