I read an interview with Brian McCarthy where he mentioned learning in his early career about using the furnishings and artwork in a room to build a skyline that moves the eye around the room. I love the term skyline, by which he means the varying heights of the furnishings and artwork guide the eye around the room. It really is like a skyline in that you are seeing it as you first take in a space. I learned it as a wave - your eye should travel in a gentle wave-like motion around the room, with no drastic jumps up or down. While I think it's more common now to talk about the rhythm of a room including all the elements (colors, textures, shapes, positions) which guide your eye through a room. But I am still a believer in the importance of the basic "skyline" effect.
An example of this is the bedroom at left where, if your eye was going around this room from left to right, it would start at the lamp, go up to the artwork, straight across then down to the lamp on the right. To be truly effective, this gentle wave-like motion would continue throughout the rest of the space.
Windows and window treatments should also be incorporated into the skyline. This can be a little trickier with very tall windows, but a little careful planning should do the trick.
Of course there are many variables that are included the rhythm of a room. But I believe the "skyline" is where it all begins.