Looks cozy. Window coverings would depend upon how the space is used:
Room-darkening shades for watching TV in the daytime.
Privacy shades/room-darkening shades if guests sleep up there or it’s an gathering spot after dark.
Light-filtering shades to reduce glare of the sun or street lights during the day.

Yes, I have used fabric room darkening shades downstairs . I will likely keep the same idea throughout. Have you any thoughts on a better room layout? Thanks so much!