I love pattern or anything unexpected on stairs. We should treat these areas as rooms as we use them everyday and give them some extra details. I have been toying with doing something fun like these images with my stairs. Most of these ideas are easy to do and not costly.
From Dash and Albert available here are so easy to install. You can have it done professionally or a staple gun will work too. Big impact for reasonable price.
So many great ideas that you can add to stairs to give them life and personality.