I've decided on a statuario 12x24 porcelain tile for both the floor and walls of my customer's bathroom - polished on walls and matte on floor. I've recommended stacked as their space is going to be very modern (including LED mirror and LED niches) and everything is white (vanity, vanity top, walls).

Their bathroom is about 9.5' wide by 14' deep (i've attached a very basic drawing, ignore the square shaped tile).

I'm wondering not only in which direction I should stack the tiles, but should I do the opposite direction on the walls for an interesting dynamic since everything will be so white, or would that out of place? We are also incorporating small hex tile in the shower area to accommodate the slope for the drain.

My thought is definitely horizontal on the walls (so 24" columns) to help broaden the wall meeting the slope, but then maybe 12" columns on the floor leading to the window? Or are we better off matching the 24" columns on the wall....

Thanks for your help