Runners are practical and stylish additions to any staircase. Before selecting one though, you want to consider your other area rugs or carpets that are in view of the staircase and make sure the runner will coordinate (not match) with them.
A runner should be wide enough to cover most of the main section of the stair, leaving about 3 inches on each side (from edge of runner to wall or baluster).
Choose a flat weave carpet rather than a cut-pile or plush carpet. They install better.
Dark patterned runners are more forgiving and will hide a lot especially if you have kids and dogs. But, a light to medium tone is always a classic choice.
One of the most stylish and affordable rug companies I know is Dash and Albert and is always a good place to start.
The next couple of days, I'll be researching some sources for my friend. If you've had any luck purchasing runners and want to make any suggestions - they are more than welcome!! Also, we'll be sure to take some before and after pictures!