Yes, you should have a more neutral wall color as it will really let your other purple elements pop more. Stick to purple choices that are easier to replace than a back splash.

The taupe countertops are nice. Have you seen all the new choices of backsplash tiles that are available currently? There are so many beautiful ones, there isn't a need to settle on white subway tiles. Venture out to the big box stores or flooring showrooms and take a look... There are tile caps of all sizes to finish off the ends. A nice one is called a tile liner, and it's about 1/2"-wide. There's also metal strips that can be laid in to finish the tile, it looks very nice. They are called: Schluter Systems 0.375-in W x 98.5-in L Aluminum Commercial/Residential Tile Edge Trim and can be found at Lowe's. They come in different colors.

Your layout for you kitchen looks really good and would fit well with the mixture of black and white cabinetry. With the lament bench top, we would suggest melamine (entry level cabinetry) or acrylic bench top, which can come in high gloss feature or matt. The matt surface would go lovely with your choice of bench top, and acrylic is also a affordable cabinetry material. Below are some examples of how Reno4u has incorporated both black and white cabinetry together, without making it to dominantly dark. We feel as if these examples would be perfect for your layout, and depending on if you want more black cabinetry or white you can go either way. This design above is an example with more black than white, can be made matt or gloss with different handles/splash back and wallpaper. With a u shaped kitchen similar to yours, however from the pictures you provided your style may include different design below the island bench. Another kitchen designed by us which shows more white than black, with a bar built in which may suit your design better. We hope this helps you, please feel free to call us on 03 423 9067 and we can provide a free quote for materials and kitchen design, and help you finalise your design further. :)

Which would look better tiles or glass and what colour? Would it be best to cover the whole wall, half wall under the range hood or just between the range hood and cooker?