As a paint consultant for Certa-Pro Painters, I have helped many of their customers choose their wall colors and one of the challenges many face is determining where and if a paint color shift is appropriate. Continuity is important on the ground floor, but color can help "zone" a big open space, separating the kitchen area from the great room, for instance. There's no need to stick to a single color or even a single color palette that is either all warm (reds, oranges, yellows) or all cool (blues, greens, bright whites). However, if dustier, muted values of colors are selected, there's a better chance the colors you choose will flow into one another throughout the space. A good rule is to lean toward colors softened by a bit of gray. Save those brighter saturated colors for accents and introduce them in small doses in the furnishings.