IMO too many finishes I like 12 x24 tile on the floor and the shower walls to match then a smaller tile for the floor can be match or be a different shape I dislike niches in showers and have no idea why shampoo bottles should be high lighted and those mosaics are a PITA to clean,.Keep finishes simple as few grout lines as possible no niche just a nice caddy and then you can add any color accessory you want at any time

There are team no niche and team niche around here. If a niche is done well it is a great place to store shampoo bottles and products. I dislike plastic or cheap metal caddies in my bathroom (had them for years and you always have to replace them) so we went with niches which make it look finished in my opinion. I used same tile on floor and in shower (different sizes though) and a mother of pearl look in the niche. How big is your bathroom?

Photos during construction of the niche

This is what a glass mosaic similar to the one you like would look in a niche.