Trust me they won't be easy to clean. It scares me thinking about this. Next time I'm going to minimise grout in the splash back choice if possible as this is the part that is hard to clean so bigger tiles are better and definitely gloss finish for ease too. Good luck.

I work as a colourist and the easiest method for a upmarket look is to choose an exact colour to match one of the colours in the tile. I would take the tile to a paint shop and get the colourist it match exactly one of the greys in the tile. Make the depth of the colour a light version. All white walls are on the way out. Lappatto tiles usually have some texture as they are semi polished. This is the latest look in tiles as they give a shine without the maintenance of polished porcelain which had been in. They are usually less slippery than satin or polished tiles depending on the brand.

Some baths are more suited for shower baths than others. It depends on the flattish standing room at the bottom of the bath. Some baths are quite curvy and narrow. Make sure you stand in a showroom bath to see if it feels too narrow (without your shoes). You will need a four flange bath for tiling and waterproofing in your shower bath scenario. https://specify.caroma.com.au/products/baths/vivas/vivas-1675-anti-slip-bath Best of luck with your planning, Dr Retro of Dr Retro House Calls/Dr Retro Virtual Visits

I think you need shelving either side of fire. Just something simple to add interest. To many surfaces, I think, already for adding tiles. If you want to put something on the fire place wall, then the clock needs to find another home. And the tile surface could be similar to the hearth. Either dark wood or black, floating shelves. Then your favourite things can be displayed. This looks like the same room you posted a while ago. The single wing back chairs would look good in this room again. Facing the fire. Then a light coloured rug to take away from all the black. Gold accessories to match your side tables. And if the plants are artificial, I would remove for something larger and real. For your window near the fire, A solid window treatment, eg: roller blind or shutters, would work. But if you don't need anything on that window, then maybe just a pelmet to finish it off.