The first image looks very serene. Scrolling to the second image I audibly said ”Ooof”. It’s too much impact, maybe not what you want in a bathroom? I do like the varying tile shades in the last image, like shadows on a pond.

I would simplify by choosing one stone as the dominant feature and letting the other materials support it. If the Calacatta Viola slab is the focal point inside the tub arch, use a quieter, more consistent surface for the vanity and shower surround; repeating a strongly veined stone in several large areas can make the walnut and taupe tile compete instead of connect. Before ordering, place full-size samples together in the actual room in daylight and at night, because warm plaster, walnut, brass and taupe can shift the apparent undertone of the stone. For the arch, a slab will usually read calmer and make the curve feel more intentional than small decorative tile, but ask the fabricator for a dimensioned seam layout, edge treatment and vein-direction drawing first. Also confirm how the stone will be supported, waterproofed and sealed at the curved transitions. If the slab needs several awkward joints, a restrained tile with carefully planned grout lines may be the cleaner choice.

I LOVE marble = I love the drama of the stone slab over the tub. However, I would NOT use two different marbles in the same bathroom (actually, it looks like three different types in the renderings -(i) vanity countertop, (ii) floors + inside shower + on shower bench, and (iii) inside of the arch over tub).

Calacatta marble has veining - some types have very dramatic veining and other types have less dramatic veining - however, they all have visible veining. Some of the marble in your inspiration photo looks like a different type of marble than a type of Calacatta.

I would use a dramatic slab of Calacatta marble other than Calacatta Viola - while it's very popular right now, it is very limiting if you would want to change up the color a bit in your bathroom in the future. I like the marble shown as your vanity countertop - I would use the same for above the tub. I would use microcement around the the tub arch + inside the shower. Personally, I don't like shower benches - they are cold = not one sits on them + they tend to be a place where leaks occur. I'd rather have a foot rest for shaving or a teak stool.

I am not sure about the tub. While I like stone tubs - I'd probably go with a more neutral color.

However, if you love the Calacatta Viola marble - you should use it - however, I'd use it for the countertop also + bathroom floors (if you want to use marble on the floors). You need to make sure that the color of the tub works with the colors of the Viola marble veining.

Yes, the idea is the same marble throughout. These images were created in AI ChatGPT, I believe, so it somehow made the marble look different on the countertop and in the shower. I def. will do microcement or limewash around the arch.

Well, I love marble with dramatic veining - so, I think the bathroom will look beautiful!

If you don't want to overdo the marble - I wouldn't use it inside the shower. I would do the waterproof microcement/specialized plaster inside the shower which will then be repeated around the arch over the tub, Marble can be an issue inside of a shower for some people - my understanding is that microcement/plaster is an easier finish to maintain inside a shower. Either microcement or plaster will provide a natural looking finish that will complement the natural stone marble on the arch/countertop/floors.

If the stone tub is a similar shade to the microcement/plaster + complements the marble slab used for the arch + countertop + floors, it will look nice.

You don't want to use too many materials. You also don't want to have too many "stars" in the room. The marble will be the star - the other materials will complement the star.

Do you have any pictures of microcement used inside a shower?

For the rest of the bathroom floor, I’m thinking of using tiles in a similar tone—maybe something with a marble look or that complements the wall color. Real marble might be too expensive for the entire floor.

For the shower floor, I’m thinking of using smaller tiles in the same shade so we can maintain the proper slope and water flow toward the drain.

I would like to see the actual bathroom please . For me what you show is a bit taupr overload but seeing the real space is always helpful

This is what my current bathroom looks in AI cleaned.

You will create the niche how? With a door swing toward the tub and already close to the shower? You will center it......? move drain etc?

There first several images just seem two brown. Brown is not my first choice for bathrooms.

Random thoughts:

- I like the first layout. The tan /brown isn't trendy /cutting edge, but it's calm and relaxing. The colors are well-balanced, and it's something that'll be lovely for years to come. You can bring in an accent color through floor mats and linens -- and you can change that color on a whim.

- I dislike marble, but -- even if I didn't -- I don't like image #2. It jumps out in a negative way. Is it "too strong" for the rest of the room? I just know I strongly dislike image #2.

- I like the skylights. They're an unexpected luxury in a bathroom. The light in this room really is lovely, but how did the door in your current space turn into a window?

- Do you have adequate space to clean around the tub?

- I would downsize to a single sink, which is more practical -- I never like duplicate sinks. This would allow space for a small linen closet.

- Still on the sink: I love wall-mounted faucets (for looks and ease of cleaning), but I have read that getting them to match for duplicate sinks is very difficult. Ask your installer about his experience, as these are fairly uncommon.

- I personally would go for a different sink mirror: I'm very short, and the tall backsplash + the oval shape would mean I'd be able to see my face but probably not my upper body in that mirror. A mirror that's arched on top /flat on bottom would still mirror (accidental pun -- ha-ha) the tub's arch, but it would give you a larger view of yourself.

- I don't see any outlets by the sinks. Be sure you specify where you want these -- don't leave it to chance.

- Is the shower door going to open without hitting the tub /stool? I notice that turning on the shower will require entering the shower enclosure /subjecting your body to the initial cold spray. With so much glass, I don't see any way to change this.

- I would double (at least double) the storage niche inside the shower. I wouldn't mind seeing a wall-to-wall ledge above the bench seat.

- Having just had to help my mother wash her hair after she had surgery, I suggest you dump the bench seat /go with a moveable stool. Because she has a stool, she could get herself seated on the stool / face the back wall, and I could step in behind her, maintaining her dignity. You couldn't do that with a built-in bench.

- Can that shower head reach all the corners of the very large shower /make cleaning easy? I'm usually the one saying, Simplify!, but -- in this case -- if the spray can't reach all the corners, I'd want a second hand-held shower head.

- Thinking practical: Where will your towels hang for the shower and the tub? Be sure the hinged door doesn't block access to your towels.

- I see you have a hand towel hung in a practical spot for one sink, but the other sink has a hand towel hanging on a glass window? Hmmm.

- Similarly, where is your trash can? your hamper?