All of our bathrooms have windows that face the back of our house.
Nothing but trees to look at.
I have tried to hang curtains there, but I just hate how they block so much of the natural light. Even small roll-up shades hide enough light to make me rip them down a few days later.
The above picture is one I made for our master bath, using twine and linen. I just glued the fabric to the twine.