We chose the Indoor/outdoor diamond ivory pattern. We had 3 runners (2.5' x8') installed for 14 stairs. ($275 total). A great return on a not so huge investment, and if we want to change (as will probably be the case in a few years, it is not like we spent a ton and would feel bad tearing it out!) We DID have it professionally installed.
How to Remove an Old Glued Down Indoor-Outdoor Carpet From a Patio
A majority of indoor/outdoor carpets sold today are flatwoven of 100% polypropylene (backing and surface). This type of construction and fiber usage makes them highly colorfast and highly resistant to fading due to sunlight and UV exposure. Stain resistant, these types of carpets are easy to clean and maintain. In addition, these flatwoven carpets are mold and mildew and water-resistant.
Functional Flooring - Carpet squares are comfortable underfoot, attractive, and easy to replace if an area ever gets stained or damaged. Just pull up the affected ones, and leave the rest in place. (And won't be slippery if water is spilled.)