Using the same floor for the whole bathroom usually makes the room feel bigger. It’s a nice mosaic tile. I’d use it throughout.

The mosaic would be a good choice, but it's probably a lot more expensive than a solid color larger format tile. So if you don't like the mosaic look or the cost is prohibitive, use a tile that matches the white in your mosaic tile or a blue-gray could also work. If you go with the white, make sure it doesn't clash with the white of the vanity. Unless you have a no threshold shower there is nothing wrong with using something different on the floor than what's on the shower floor.

you're aware of the care invovled with using marble on the shower floor, right? It means you can't use any random cleaner on your wall tiles because it will wash down onto the marble and etch the finish. even 'green cleaners' do this. you'll need stone safe cleaners only.

And, if anyone dyes their hair darker or fun colors, the rinse off from those colors will stain the marble. every 6 months apply a good sealer to that floor tile. Better yet, apply this sealer after the marble grout has dried. good for stains, but the marble will still etch.

if you used the same mosaic tile on the outside floor, you'll basically get this look

what about a blue/white cement Hex tile (or porcelain that looks like the cement) ?

Are you doing a herringbone layout w/the blue tile in the shower? you could use that same tile on the ouside floor like they did here

or, do a white or gray larger hex tile
If you don't mind more marble, this is Thassos (the same as your mosaic) in a 10" hex tile.

this one is a matte finish

you could use a dark blue or gray larger hex tile

diff tile, buy I really like this look too

lastly, you could get a neutral generic porcelain tile in the same tones as your mosaic. this one is a 12x24

for a clients bathroom he chose to do a charcoal floor tile w/his blue shower tile

he had a more modern white vanity w/quartz top

I did a stacked layout w/the tile, mosaic in the niche, and a porcelain charcoal herringbone tile on the floor

A lot depends on the size and layout of your bathroom. A small scale in a large bathroom can look busy. What will the entry of your shower be? Curbed? Curbless? How will you be laying the pattern on the blue subway? All of these need to be considered before choosing the flooring.

Beautiful choices! A white plank tile with a blue undertone would look nice and simple and wouldn’t compete with your other tiles.

I'd stick with the same as the shower floor.

And I've had marble in my shower and for my floors in my master bath for 3 years now with no issues. I made sure all my tile was honed, not polished so if anything etches it, I don't even notice.

Now paint color 😩

looks good! I like it.

are the ceilings high? if so, I'd do a dark ceiling to match that tile.

It looks great!