The plain white hex feels most appropriate to me.

You can get mosaic tiles from AMERICAN OLEAN

https://www.americanolean.com/products/mosaic/unglazed-mosaics

MOSAIC PATTERNED TILE

https://www.daltile.com/Mosaic-Tile

I love your bathroom!

I would keep your vanity as is - it looks terrific!

Please don't change the vanity. Paint it whiter to go with the tub. Get white small hex tiles that go with the tub. Leave it at that and let the vintage tile be the star of the show.

Thank you for the feedback.

I like the idea to paint the vanity whiter to match the tub. Should I try to change out the vanity hardware and faucet too? Do you think gold is too much or stick with nickel color? If I did gold would it make sense to get a vanity light to match?

Gah what a fabulous bath! i would go chrome for the faucet, clean and crisp and era appropriate - for the vanity, I’d do low key wood knobs painted to the match the vanity

agree that crisp clean white will help the tile shine 🤩

Since there is so much already going on in your bathroom am going to suggest a plain white tile for the bathroom. Although not generally a fan of hex tiles what you are showing in your photos seems to work pretty well.