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...

Susan, we installed our wonderful new kitchen just over a year ago and still we find the tiled wall/splashback the best feature. The kitchen colour is charcoal and depending on the light of the time of day it looks dark grey or blue.....so our choice of splashback had to be rather neutral. we decided on a clear glass subway tile and the most wonderful part of this is that the natural glass colour (faint green tinge) comes out and this is most complimentaryto the cabinetry colour.....

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

Do you have any other colours in your colour scheme in the rest of your house that you might like to incorporate? I think your current colour scheme in the kitchen lends itself to quite a few different options .... black & white encaustic tiles, smoky glass mirror splashback, a coloured sheet of acrylic or check out the range of tiles from Southern Cross Ceramics.... they make it hard to choose! So many beautiful options, colours & patterns .... they have a visualizer too so you can see how it all looks :)