A Runner That's One with the Stairs
A painted staircase "runner" can bring bold color to a small space.
Try a shade that links the upstairs and downstairs, or consider a combination of tones that packs a visual punch, such as these stripes. (On a practical front, dark hues will cover any dings.)
Use painters' tape to ensure a clean line, and primer and oil-based enamel paint to withstand the traffic.