I've noticed a recent trend of the vertical color on the island matching the vertical color on the splashback. Liking that trend. So I would say go with the turquoise glass splash back color. Deepen it a little so the hue is closer to that of the floor. Cant tell from pic whether island cupboards are the same color as cupboards above the splashback. If they are, all the better. That then brings the turquoise/white combo forward into the room and gives some unity.

I would paint all the brick everywhere warm white...satin for occasional cleaning. That done I think everything else will look OK because the colours are natural. New doorknobs are always good. You could if you wanted paint all the bench and cupboards white or rich cream as well....MUCH more spacious effect. there is a product you put on first and wait and paint...Hardware will knw...something like PSo

Ah - this takes me back to the 70s, when I decorated my teenage bedroom around a bedspread with this blue and green combination! So .... very retro and cosy. For me, it's a better cold climate or winter colour scheme. I like it, but think I would tire of it more quickly than a more neutral scheme.

It depends on age. If existing bath recently remodeled then you want a link of some sort, this could be colour scheme. But if the other areas and kitchen need remodeling I would go for a look that you might want to move towards.