Have u thought about a glass splashback?its very easy to clean,I have used red,but u may like a more subtle colour! We put in black granite bench tops when we built the house 17 yrs ago,they still look fantastic but they are a nightmare to keep clean,I would definitely change them to a white Caesar stone if I could!!

This is going to come down to what your space is like, light, how you use the kitchen, how does it relate to other areas of the house ie. is it open plan, so needs to complement other areas such as dining & family? Here are a few examples of backsplashes with concrete benchtops. Depends on your personal style & taste as to what appeals to you. My 1st reaction was marble, it would give interest & movement but without knowing what else you have going on in the room...

I'm going to suggest these grey Montage tiles. I think the Como tiles are nice too. Dark grey will add drama and balance out the dark sink. The mixed tones will tie in the variations of grey and silver in the bench tops, appliances and glass door frames. The stone/slate look will add a natural element to complement the wooden floor and balance out the laminate. If you do go for colour, I like Bernadette's suggestion of complementing the glass colour. A tile that looks like pale jade might be nice.

Thank you. I had hoped you would get some comments but am glad you are happy with the result.