Add a dark wallpaper into an area of the house that you would tend to just walk by. Why? Because adding such statement pieces in a smaller area, turns the room from drab and boring to a truly magnificent space. By using darker wallpaper it adds a luxury element to the room because the dark colours create a moody cosy atmosphere.
Picking a smaller area such as a washroom or powder room allows your inner interior design to come out. Because it is a space that is otherwise forgotten about it allows you to be more creative with it as no one has an expectation on what the interiors should look like.
If you do not want your room to become too dark you can add some contrast to the room by incorporating lighter tones throughout the flooring, finishing and fixtures. Let your inner interior designer daredevil come out and go for a darker bolder wallpaper. It will work in your favour.