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?

I feel it's too heavy looking for your room. You say it's a very large room, so you don't need it to make the room feel larger. Perhaps look for a picture/painting.

I agree with Diane's ideas! Grey is a nice color. The only thought I had on having a corner sink cabinet, you may not be happy with it in the end. You have a little corner, and the sink may be too small for you in the end along with not having any storage space. If you can't find any curtains that you love, try a cheap roller blind for now. It will give you a visual look and an idea if you want to stay with a curtain or going a bit modern with a patterned blind or even a roman type shade. It could turn the cozy look into a clean modern look. Framed mirrors are expensive. Call a glass company in your area and have them give you a price on mirrors. It might be quite nice to take the mirror down, and replace the wall there with a complete wall mirror to fit, stopping the mirror at the vanity, and continuing the mirror across the vanity between the sink and window. It will make your bathroom feel much bigger, even though you wont be able to see in the mirror over the sink. Close up the vanity doors with new door. Use props first (white poster to cover up the doors) etc. before you buy anything! Stick on tiles are a great idea! They clean nicely and look great. Although I wouldn't go with the wood look. Your bathtub tiles are old fashioned, go with a stick on floor tile that is easy to look at, try to get samples first. Remember Gray is a sleek clean modern color. It is not a cozy country color. If you don't like the grey in the end, maybe a real pale blue or butter yellow (that would be more of the cozy cottage look).