I enjoyed Laura O. Foster's The Portland Stairs Book. She provides short descriptive and historical accounts as well as photos of the various staircases about town.
Among my favorite are the more remote and sometimes unkempt stairs around Forest Park, the wooden stairs leading down from SW Montgomery Drive, and the SW 10th Avenue pump-house stairs. There are also the elevated sidewalks built in Linnton during a different era, and some of the SW trails circa SW 45th winding through forests. The more residential Alameda Ridge and NE 50th steps also have a certain charm. She lists as most perplexing, the two staircases hanging off the Morrison Bridge which allow pedestrians to walk unhindered by car traffic.
Among my least favorite: the stairs leading to the Broadway Bridge, and those in the Multnomah County Library.
The author also provides a list of stairs, each of which she walked while researching the book.
The Portland Stairs Book by Laura Foster; Timber Press, 2010