I would consider floor to ceiling curtains on the triple window on the back wall and shades that fit inside the frame on the side wall...selection depends on if privacy or black out is needed...your room seems simple ..clean..elegant..but would benefit from a softening element for the curtains...such as a sheer but organic textured fabric with some interest in pattern while not nescessarily multi colored...the shades could follow that vein by using a tortoise shell bamboo material ..or something tailored in a monochromatic stripe...it you wish to introduce color all the better to add a little warmth to the softness

Curtains and shades are a the perfect way to add a little excitement to a pretty neutral setting such as yours..let loose a little with this element..express yourself with a bolder statement

Think lime green or Aqua ...or sky blue ..or watermelon red