That is a tough one it can depend on many things that are specific to each room.
Generally, amping up constrasts (stark white ceiling/navy walls) lessens any feeling of expansiveness a room may have. By keeping the color consistent, designating a logical line for the ceiling and walls, and chopping up a room as little as possible is the best way to maximize every visual sq. inch. A creamy white, like Sherwin Williams Creamy or Ellen Kennon's Classic Cream (avialable thru ICI/Dulux) are two good ceiling colors. They have a definite edge of warmth.
The "it can depend" part is important though too. Sometimes it's really cool to punch up those interesting slopes, alcoves and window seats by bumping them out with color. Limiting the contrasts by using one strip of color is an option, i.e. do the walls in a color from the middle of the strip and accent the interesting areas with a darker color from the same strip.
Take a digital picture of the room and print it. It will give you a different perspective. You can even experiment with markers or upload the pic and use one of the at-home virtual paint programs.