We have the black mirror splashback. We love it and it soooo easy to clean

Is there something in the room you want reflected back that you love looking at? If not, why don't you find a nice piece of art work for the fireplace so you have something to enjoy rather than looking back at your other wall?

Huge artworks and mirrors that are leaning would still have to be attached at the top somehow, wouldn't they?? Surely they would be dangerous otherwise, especially in areas prone to earthquakes (even small ones) and in homes with young children. Imagine something that size falling onto someone!

Add colour . Please add colour haha . Just a thought though , instead of paint ( its a bit hard for me to visualise everything from your description -- I am a visual person ) how about maybe those translucent blue looking tiles ( yes , I know , extra cost ) , you may even 'frame' them in the white tiles to tie in with the shower , or possibly do the blue instead of the white , or even do the shower in them , and have the rest your 'white' walls . And when I say about those tiles , you can get them in square or subway or even long skinny ones , or even long and skinny but with long skinny darker blue and brushed ali ones too -- in other words , have fun and add interest !