We chose a combo of black sides and walnut shelves. They remind me a lot of the Tomado shelves, and provide some contrast to the pale walls. Walnut very easily changes color when exposed to daylight and sun, the color becomes warmer and very similar to teak. This has been the case with our other walnut plywood furniture, they are now very similar in color to our teak pieces. Which, of course, is no disadvantage.
I'll leave you with some images of the String shelves as well as a few other living room snaps. I'm noticing how big my living room looks, it's really not!!