Mark
Most folks I know would tell you the long direction of the longest room in line-of-sight. However, if you are covering multiple rooms (living, entry, dining, den, etc) you can pick the piece you want to accentuate AND KEEP CONSISTENT WITH THAT. We do a lot of "whole house" wood flooring in Texas these days, and can make almost anything look good. Lastly, the width of plank and distressing level can also play into the decision. Can you send a picture of the space?

--DRG

We just put in new floor next to old floor and made the boards go the other way than they originally were so that they could easily go under the existing radiators. In our case, the switch in direction at the threshold to the adjacent rooms is not weird since the old floors have borders (that look like frames) around the edges. If anything, it's the contrast of old/new, smooth/distressed that is most noticeable.

Dallas Renovation Group has great points. I can add that when doing a large home we have even changed direction in different rooms, where necessary, by laying the boards (same color) with a border pattern. If you post pictures we can be more specific with our suggestions on both direction and size of plank. Good luck!

Old meets new.

Thank you for the response! The main living/dining/kitchen areas are all in a row and there a is a clear "front to back" feeling of the entire first floor with respect to the main windows, and visually there is a clear "longways" that would normally make this decision easy and in line with your response. What's throwing me for a loop is that the front door and small foyer is off to the side of this main space. I'll see if I have a photo that properly demonstrates visually what a person who just walks in the front door sees...

Long ways, which I was worried would make room appear too narrow, but the "rug" breaks it up. The border is cherry while floor is oak, so the border will darken over time.