There are many examples on houzz of contrasting counters for perimeter and island. For example butcher block on island and stone on perimeter or a solid color on one and something with movement on another. I would only mix two stones if one had movement and one was fairly solid. The stainless on perimeter and something else on island sounds good to me. Here is a pic of stainless counters with what looks like a stone breakfast bar. (I hope I understood your question right). http://houzz.com/photos/3137660

The first thing I require each of my clients to do before even starting the design layout is to choose their appliances. Your kitchen designer will need the manufacturer's specifications to know what size to make the cabinets to accommodate them. Be aware that there is required distances needed around and island, typically 36" up to 48" depending on placements of appliances. This will dictate the size and shape of the island. Clean lines, simplicity, innovative materials like glass countertops, exotic woods or Italian veneer slab doors, flip or lift up doors can add unexpected touches to a modern/ contemporary space. Here are some photos of one of my favorite Euro Modern kitchen I did for one of my clients not long ago.

~$400 including expedited shipping. My GC just had his regular countertop guy do them, which wasn't great.... he had trouble making clean cuts. If I were going to do it again I would have pressed for someone with expertise to cut them. You can see in the image that the facing is not made of the stone peak, because too much was broken during the cutting to make the mitered edge. I'm a little bummed, but mostly pleased with the surface (which is the important part) thus far.

The all black kitchen looks scary as. Maybe because there's no lightness in there at all.