Here is a close up of the tile.

Your tiles choices look great together. I don't think your bathroom is too small for the 24x24 floor tiles.
My daughter's bathroom has a floor area that measures 63 inches by 76 inches, so even a little smaller than yours and she used 24x24 tiles. I think it looks great.

Since your floor tiles are almost a solid color if you match the grout to the color of the tile and stack the tiles I bet you will barely notice the grout lines in the room. It will almost look like one solid piece/slab of flooring so I think it will look fine with the 6x12 tiles on the wall. My daughter stacked 12x24s in her tub/shower and that is more contemporary looking than using the 6x12s the way you plan.

Thanks Badgergal. Your picture is very helpful and I will show my husband and see if he likes the look.

Here's one more to show him.

Good luck in your remodel

On my screen the color looks good with the calacatta tile. My thoughts about cutting the calacatta tile into smaller pieces is that you won't see the veining as nicely as with larger pieces. Something to consider.

I linked a post by KevinMP and his calacatta tile in his kitchen. the before pics have a green wall with 3x6 carrara looking marble backsplash. The remodeled kitchen has 4x4 calacatta. To me the smaller calacatta tile breaks up the veining. Something I noticed when I first saw his posting on the kitchen. The bathroom I believe is calacatta as well, and heavily veined. It is more flowing to me because the tiles are larger and display the vein better. Just something to consider. It might not make any difference. Do you have the option of cutting a few up to sample the layout in the smaller format? Might be worth the effort to check the look before you commit.

Here is a link that might be useful: KevinMP's calacatta kitchen and bathroom.

I personally would not cut the Calacatta tile in fact I would go the other way and go with bigger tiles. You get a better true effect of the tile and the beautiful veins. When going smaller it tends to get really busy and almost frantic looking. Look at a lot of the sizes installed to see what you like best.
I like the tile choices they go well together.

So, we have already purchased the calacatta tile in 12x12, so larger tiles are not an option...not to mention I typically don't see large format tiles put on a wall as tile wainscotting.

We will give serious thought as to whether we cut the tile or leave as 12x12. Since we are storing the tile I guess we could lay it out and see how it would look either way.

The decision we need to make now is on the floor tile and what size to order. Any other thoughts on floor tile size....especially if we consider keeping 12x12 marble tiles on the walls?

Thanks!

I love those two tiles together! I had kind of envisioned that kind of floor tile for my recent hall bath remodel, but I ended up with something with a little more variation (thanks GW!). I still wonder if the more single color would have been better, but my tile is growing on me. I don't think the size matters. I kinda wish I'd set mine on the diagonal, but that's just normal second-guessing myself.

For me, if it was my floor, in the large scheme of things, the floor tile size would probably not matter. I think it is wise to use porcelain for the floor, the resent revival of Pipdogs old tread, with her white marble bathroom, is telling. Pipdog responded to recent posts and reported she found the marble on the floor very hard to maintain.

Are you doing the tile? If it was me doing my tile I'd vote for 12x12" or smaller, LOL. I have a lot of lipage on my 12x24 shower wall because it was too big (I am assuming that is the reason) for me to handle. I did a floor and a wall. On the floor I used a leveling system. People have liked and disliked them. The system I had was a hassle, so I free handed the walls. I did have more lipage on the walls but then the tile was rectified, whereas the floor had a very rustic bevel at the edges. This might have helped hide the lipage. There is a reasonably priced system at HD that is doable for a smaller project like a bathroom. I have heard people like it. It is simple to use, but the wedge system can hurt your hands if the project is very large.

Here is a link that might be useful: Pipdogs marble bathroom, august 2012.