Architecture Comes First!
Creating the palette using the relationships between the colors is step one. Where then to apply those colors is step two!
So often, our clients will begin their consultation with telling us where they were thinking to put an "accent wall." After they've made their declaration, of course we follow up with, "Why?"
Without a doubt, we've found the phenomenon of accent walls to be completely overused and quite frankly inappropriate the majority of the time. Being afraid to use a rich, fun color on every wall is not the reason to put it only on one wall to create said accent wall.
Rather, stand in different places in the room. Feel the energy of the space. Be still, blur your eyes, clear your mind. Do you feel or see one wall that anchors the space or perhaps juts into the space? If yes, this would be a place to consider using one of the more bold colors in your palette to serve as an accent wall.
If however, the space you are painting feels very contained, box-like, chances are, using a color on only one of the walls will feel lopsided and out of place. The millwork or trim in the room will determine this greatly! Typically, if the room has crown molding or a picture rail, creating an accent wall will simply feel weird because the trim creates a band around the entire perimeter. As a basic rule, each space will feel best if the walls flow along with the trim.
When we want to use more than one wall color, we determine how the architecture creates different spaces, and we change colors for each of those spaces. For example, use one color for the living room, and switch colors on the walls that begin the adjacent hallway.
Certainly, the space is created by different planes coming together. Architects design those planes intentionally, determining how they will create a space. With that knowledge, it is so obvious then that breaking or dividing a plane with color would work directly against the architecture. Even switching a paint's sheen on a plane is not advised. Just last week we saw once again how someone had used a high sheen paint on the ceiling in the kitchen area and switched to a flat paint for the rest of the ceiling that flowed through hallways and the living room. The ceiling throughout all of the communal spaces in this home is one plane without a break, therefore, architecturally, the ceiling color and sheen will feel best when it is the same throughout.
Color SUPPORTS architecture...not the reverse.