We feel the best option for a bathroom window is a cellular shade. I also would recommend a cordless option. because most shades are over the bath tub and hard to reach, a cordless option allows a much nicer appearance - and since it usually is in the closed position and not raised or lowered - the cordless has no cords showing in the closed position. Also, because other products in the closed position, create a dark atmosphere, the light filtering cellular shade lets you maintain light but still have complete privacy (check privacy option to make sure your selection is rated private)
They are easy to maintain also - and especially good around moisture.