What direction do you want to run the floor? Parallel to the primary light source is the standard. For example, observe the direction of the daytime sun in the room and layout the planks lengthwise with the light. Another consideration is to guide your visitors first impression of the room by running the planks length wise from the front door. One of the popular trends today is to unify the flooring by installing the same flooring throughout each level. You can accentuate the open look by running the flooring parallel to the longest distance between walls. Another approach is to separate areas with herring bone, basket weave, ashlar, and stagger patterns. Or, try diagonal planks to create interest and guide a visitors attention.