I have a window just like this in my master bath. These curtains look perfect for privacy and style. (pottery barn)
one way mirror film - use this on the doors so I don't need to mess with curtains? Have to think about this...
Frosted Window Film - Great way to keep natural light AND privacy. I used this on our hard to curtain side lights!
US $24.99 New in Home & Garden, Window Treatments & Hardware, Window Film
DIY - with frosted Shelf Liner Paper! makes Frosted glass for master bath windows
Inside mount shutters example in bathroom window
Decorative Screens - options in metal, alum, plywood..: