That totally depends. If it's an enclosed space and it has trim I would go ahead and paint all the walls this color (it's so beautiful!). If it's an open space, a single wall can help demarcate the dining room. If you don't have crown moldings or other trim, you can always add a simple chair rail like the one here. It really depends on what you want and what the room is like. But my impulse is to paint the whole thing! And post pics when you're done.

What is this paint color?