I think it depends, actually. In our living room the tongue and groove ceiling and the floor will run the same direction (floor not yet installed). Big room. On our original porch on older part of the house, as in most porches, the tongue and groove runs longways, the floor runs shortway, typical for an older home (though not always). Looking at your drawings, I would run them to the fireplace and I'm assuming that your ceiling is running the same direction. I can feel the movement/energy from top to bottom (fireplace to range), the other direction would feel static to me.

T&G prefinished flooring isn't usually available in long lengths. That means there'll be seams at the ends of the boards making it look like a floor on the ceiling. Paint grade t&g, usually bead board, is often available in 12' and 16' lengths eliminating or at least reducing the number of end seams. It might be possible to get flooring in long lengths but it'll be expensive.

I don't think that running the floor a different direction in the sunroom would look strange at all, especially given that you have a natural transition point in the french doors. The hardwood in my house changes direction between the living room and the rest of the house and the transition gives definition to the space. I would do the transition with a single board the width of the door jamb with the turned boards slotting into the groove in the threshold piece. I happen to like the look of a turned board underneath a door where the two rooms aren't a continuing space, such as a bathroom door. My house also has a wood floor continuing from the living room into the sunroom (no door) and over 80+ years, the house has settled slightly and there is a slight slant to one board over the transition between basement and crawl space If the subfloor construction is sufficient that direction isn't an issue, I would think the hardwood would go across the width of the room, perpendicular to the ceiling. But, that's just my opinion and worth what you paid for it!

We are building our home. We have very high catherdral ceilings in our "great room" which is our kitchen/dining/living. Our plan was to have wood flooring, grey walls, white tongue and groove ceiling and white kitchen cabinets. BUT now that we have started putting up the tongue and groove everyone is saying do not paint, just clear coat it. What to do? I personally feel like it will be too much wood with the ceiling and the floor. And secondly i have no clue what wood color the floor should be or what color to paint walls??