Apparently my pictures didn’t upload correctly!

Picture #1 - bathroom floors
Picture #3 - shower walls

In the pictures you posted I can't really tell if those whites go together. How do they look in person in the light you will have in your bathroom?

The easiest way to match whites in a bathroom is to use a tile that comes in different sizes so you can use the same tile throughout. I like to use something smaller for the shower floor such as a 1-2" square or hexagon rather than the rectangles you're showing. You have to be able to be able to slope the floor toward the drain and that's easier with smaller tiles. You could use the same tile as you have specified for the shower walls for the floor (outside the shower) as long as it isn't too slippery. You also don't need to do anything different in the shower niche. It is more common now to use the same tile as the wall tile in the niche.

If you are having trouble matching whites with different types of tiles the other way to deal with it is to use something varigated instead - shades of gray or something else complementary. There is gray in the wall tile you're showing, so if there is more gray elsewhere that would work. You don't say what you're using for a vanity or counter. What are you thinking of there?

@Trisha K I am also interested in these tiles. Did you end up using these and, if so, how do you like them so far?

I didn’t end up using these tiles. I decided to get bigger tiles to avoid so many grout lines.

Thanks @Trisha K! What did you end up going with?

I ended up going with a matte marble look!