In the rowhouse where I grew up, there were no chair rails in sight until my home-making mother added them to our dining room. I was little, but I remember liking that my mom had fancy style.
Back then, it seemed the rule to always, always, always put the darker shade of paint below the chair rail. This was true in the parochial school I attended, too. A dark yellowish cream on top, army green below. I liked school and because of the Sisters I have beautiful handwriting, but that cream and combat-green hallway color combo was very hard on me, aesthetically speaking.
I’m not sure when the tide turned, but I am seeing more and more rooms with the deeper shade painted above the rail. I love the look. Please consider this when painting your space. If the furniture is a deep color or a dark wood, it stands out nicely. Artwork looks beautiful hung on a dark wall. Try it!
Sometimes the chair rail and woodwork are a third color, but feel free to use just 2 shades: let the rail and trim be painted the same as the lower color on the wall. If there is a lot going on in the room, you may not need or want a third color.
Personally, I like using different colors/tones above and below the board. It gives the chair rail something to do.
I thought that chair rails were all about protecting the delicate plaster walls from being damaged by careless chair handling. Hah! In my search for a source to quote on this important topic, I e-found a blogging carpenter man, Brent Hull. Mr. Hull has written about the classic architectural orders (yes, plural) and the correct proportions of the chair rail. It turns out that protecting the surface of walls is only a minuscule, barely-worth-mentioning aspect of the chair rail. His article is a great read (here) about the ancient builders and how they made a room feel right. Seriously, a fascinating read.
I take a moment now to thank all our foremothers and forefathers, those builders and decorators, for all their efforts at creating and perfecting beautiful, well-proportioned environments.