Direction of wood flooring
USUALLY, for the sake of aesthetics, wood flooring is laid parallel to the longest wall(s). There are times, though, when - because of the floor joist direction and lack of rigidity in the subfloor - the other (perpendicular to the longest walls) direction is better.

If the flooring is laid crosswise to the floor joists, it's easier to get the mopboards/baseboards scribed or flexed to match it - there's less ripple.