what should be "ideal" floor coloring in a bright area?
Like you say, brighter tiles make the room brighter (and apparently "larger"). Darker make it... darker and smaller. The "brightness" also depends on window size and orientation (relative to what direction the sun shines from) and room size.

You need to balance whatever is your taste with all these factors. The rest is subjective. Some people like darker rooms even if they're small, others prefer to make them as bright and apparently large as possible at all times.