I assume we're talking about wood flooring.

I had the same problem where a hallway met a bedroom. I wanted the flooring to head down the hallway and not across, but the bedroom's longest wall was perpendicular to the hallway. I used the doorway as the point of transition. In an open space, like I am doing in my home now, I plan to use a corner as the location for the transition. Perhaps you can do the same thing.

If you have some samples or you already have your flooring, lay it out a bit and see what you like. It will make a difference if the planks are wider or narrower, the lengths longer or shorter.

Most importantly - trust your gut...you have to live there and look at it for years to come!

Are you built on a slab, or is there a basement underneath? Because in the latter case, all wood flooring must be laid perpendicular to the joists...

Does this only apply to real hardwood or all flooring? we are putting down LVP

Yes and most definitely to LVP.