OK, I've reread all(I think) of your posts now and I see your point about the wainscotting not really being truly visible in such a small space. You have options, but I really think the wood plank is not the way you should go, it is very far from what was your original inspiration. I am not sure it will make you happy. I think I would do the wainscotting, scaled down to fit the space. Layout/draw specifically the layout for each wall segment, the 36' toilet wall, the long wall next to the toilet, the sink wall. This is homework that will make the difference. The marble inset band needs to be fairly wide, maybe 6", it would be just at the level of the sinktop. Carry the marble band around the pony wall endcap, you could continue it around the shower, but I think you said you didnt want to. Top the pony wall with a marble sill. My only doubt in the cohesiveness, the peacefulness of this plan, is the two cabinets you want to put over the toilet(assuming I am remembering that correctly), I think they will make it heavy. So I would want to hold off on those until the space is complete and then decide. I think a chrome(I am assuming your finish is chrome) train shelf might be better to hold towels, yes it will not provide as much storage but perhaps it could do. I think this gives you the classic look you were inspired by.

I was reading the manufacturer's sheets for cork flooring, and although they say it can be installed in bathrooms, they also say the humidity needs to never get above 60% and the floor can never be wet-mopped. A floor that can't be wet mopped seems like it's a bad choice for a place guaranteed to sometimes have drips? Has anyone here had cork in a damp environment for a while now? Also, it looks like a pro needs to put down the cork and finish in place? We generally don't hire a pro for anything. We put down groutable vinyl tile in our half bath (to replace yet more cracked tile). It looks nice, but I literally spent three weeks finding the pattern and hate all the others. My problem with vinyl is a lack of depth. Wood and stone shouldn't be perfectly flat, so it bothers my eye. I'm trying to resign myself to vinyl. LOL

O.K. so I said "luxury vinyl" no way ever. Used this in a small bathroom and love it. Many of the very upscale homes in this area are are using luxury vinyl in baths. This one has a super nice attached underlayment, a nice textured surface, and is so much warmer feeling than ceramic tile... you may be thinking more tile than plank... but thought I'd throw it out there :) Good luck on your decision! https://www.lowes.com/pd/SMARTCORE-Ultra-8-Piece-5-91-in-x-48-03-in-Blue-Ridge-Pine-Luxury-Locking-Vinyl-Plank-Flooring/1000196679

Have you actually seen a honed version of marinace? Most of it's beauty becomes muted. Hope you have good homeowner's insurance for the broken bones. Honed is still very slippery with one drop of water. Granite is traditionally flamed for wet area use. And that would be exterior. Because once that is done, it's not easy to keep clean. It grabs dirt worse than homed does. And honed grabs it pretty badly. Footprints and oily products and makeup and powder WILL happen.And show. And you will need a BIG budget for the expert labor needed to reinforce the floor and get it flat enough, and low enough to physically work. FLAT is required. There are multiple reasons that this isn't done everywhere.