The black is striking, but once is goes up the walls it's impact will become overbearing in time. The brown is most complimentary, although I fear this will outdate your Bench top quickly. The white doesn't scream out as much, although is stark in contrast, this small shot doesn't show that once on an entire wall, your line of sight only settles upon a Bench top as a horizontal plane you want that surface illuminated, and the white tile on the vertical plane will not only disappear into the space, but will also reflect any light onto that surface. When going with a white tile, the bench top will have time to be the single statement in the kitchen, until it is changed. The white doesn't have to factor into that too much. My only thought is that to take an ordinary white tile, I suggest laying them in an extraordinary manner. Change up the layout and emphasize grout lines.

Fantastic makeover that proves you don't need to spend a fortune to achieve something fabulous! I admire the fact that you have done it yourself(ves) as I can imagine how busy you must be with little kids.

If you're not using the butler's for major prep, then your main sink and fridge should probably be in the main kitchen area. I've got a Miele dishwasher in our island, beside a sink and basically underneath the prep area - and believe me, you can barely hear the dishwasher when it's on, so you that might not be as big a consideration as you imagine. We use our butlers for storage, microwave and toaster, and hiding the mess when we're entertaining (which isn't that often). It does have a sink, but we don't use it that much because it's too far from prep area. Fridge is near prep area, as are range and wall oven. You might want to take a look at some of the articles on Houzz and elsewhere on working zones, and decide how you can best organize your workflow. If you're not going to use the butlers for major prep, I would rethink where the fridge and dishwasher go.

I work in tiles all day. Glass and mirrored splash backs are on the way out. Texture is what everyone is chasing now. Lots of interesting textures and tile shapes coming in particularly hand made looks in gloss and mat. Maybe 150 x 75 mat laid in a herringbone style (45 degree) or black gloss or matt laid brick or h/bone with contrasting grout. For a modern look 600 x 300 size tiles with grooves in mat finish. Bright colours with black and cream such as red are great if you like them but if you plan to sell the majority of people don't seem to like bright colours in tiles and your colours are classic at the moment.