I'm sure you'll hear from lots of other folks but IMO, the best way to make a small bathroom look larger is to use the same tiles on the floor as you do on the walls. A larger format like your 12x24 might be a good size and will give you minimal grout lines. There are new grouts on the market that resist staining. I think something like this with a minimal amount of design would look clean and timeless.

https://www.homedepot.com/p/Opal-Beige-12-in-x-24-in-Porcelain-Floor-and-Wall-Tile-6739A/302612276

I have a 5x7 bathroom. I used 12x24 on the floor and 4x16 subway on the shower walls. You could do all 12x24 less grout to clean

@katinparadise see the pic (not sure it shows it well) but this is what a designer (maybe not her title) at the store recommended but when I look at them together, I just don't see it. Again, not a designer and don't even have an eye for stuff like this. Opinion? I like both of them separately, but not together. Both are 12X24.

why would it stress you? don't you have any opinion of what you like? What you do is pick a bathroom style you really like. Then show it to your designer or your GC person, and tell them, "make it look like this".

you should be able to go pick out tile.

what do you like? (and why does it have to be brown?) doesn't matter what you did in the other bathroom.

What stresses me out is how to know which two tiles go together. I can't even go into a store right now and look at all of my options (due to COVID-19). I am relying on them to bring me out tiles and attempting to match them and I have to attempt to visualize a white tub separating the two tiles. Please look at the pic I posted in another comment and give me your opinion if you think those two belong together in the same tiny bathroom. Thanks!

Amy, I don't care for those two tiles together at all. One is white and gray and cool and the other is warm and beige. Did you see the pic Beth posted above of the bathroom with all the same tiles? IMO, something like that is a much better option for you. I know you'll be putting in a tub, but I like the way everything just flows together seamlessly.

And which vanity do you have? Similar wood as your door? I too have a small bathroom without window, in beiges... I don’t like it. From both tiles you have to choose, I prefer the cool gray one for floor and wall (with a white tub and white toilet and warmed by some wood).

No those 2 don't go well together. I like the one on the left, not so busy, for both floor and walls

@Amy smith - Amy, What store are you working with? The tiles you posted above do NOT go together so I wouldn't have confidence in whoever is guiding you. You know more than you think. I'd stay away from browns - they can look dated and dirty. Stick with whites. Subway tile is always a timeless classic, so use it in the tub if you like it. I have it in all 3 baths. It never goes out of style like trendy items will. In a timeless bath, you could use a white tub, with white subway tile. You have a lot of options for the floor. I might use a large format hexagon in a color that you like. What will your vanity be - painted, wood, etc. The decisions need to me made with all elements so that they work together. This could look nice for the floor with a white subway tile in your tub area. https://www.homedepot.com/p/Toscana-Carrara-Hexagon-9-in-x-10-in-Matte-Glazed-Porcelain-Floor-and-Wall-Tile-8-06-sq-ft-Case-TOSCARHEX/312293449

The two don't go together, but I like the whiter one. So here is a combo that you could use
If you have a tub, forget the penny, that would be for a shower floor.

(these are all bright whites, the photos make them look on the yellow side. it's not)

otherwise, you could use the large tile on the floor, the 4x12 white subway tile laid in stack pattern on the shower. and maybe a decorative mosaic for the niche.

Or this one. this wall tile is Cloe from Bedrosians. comes in diff colors and sizes. It would look great w/your larger white tile

the blue would also be pretty. (comes in a 4x4 like the gray ones I have listed below)

here are other tile choices I saw at my tile place. see if you like any

diff colors and diff size tiles. the samples show what's avail

cement or porcelain tiles

porcelain marble look

browse through these pics of small bathrooms and see what you like

https://www.houzz.com/photos/small-bathroom-ideas-and-designs-phbr1-bp~t_712~a_30-231

Sorry, the first doesn’t have the same tile, but this:

I like Beth's idea. Find a picture of a bathroom you like, and have your decorator use those.

Daniela what is the name of the marble porclain tile in your picture?