Remember that deep colors, and especially cool ones, will appear to recede. In a small space, blues, greens or pale violets can diffuse the angles of walls and ceilings; they will seem to retreat or float.
Claydon Blue / FARROW & BALL CLAYDON BLUE 87: "Shadow can be your friend, especially in a small space. Painting a room a dark color camouflages the fact that it's small. A deep blue like this creates the perception of depth. The green in it warms it up and reminds me of those glazes on English Aesthetic Movement pottery. Lacquer it if you want more liveliness." -Thomas Jayn