I would suggest small stone mosaic

http://www.arizonatile.com/ROSA-VERONA-P823C133.aspx

A blend of colors to pick up the hues of the wood, floors, and counters. I like the brick, but prefer the glass penny tile on the left-grouted in a color the same as the light veining in your counter. I'd steer away from square-you have too many squares already. I also suggest painting the walls a medium gray color (a shade deeper than your cabinets) to balance all the warm colors you have... Wall color: SW 7018 Dovetail or SW 7025 Backdrop. Hope this info is helpful. CheerS! [houzz=][houzz=]

Because your counts has a lot of movement in it, I would suggest a simple 3x6 subway tile. A classic look that will not compete. Maybe a subway in a soft, warm rose08manor suggested above.

The tile that's there seems to coordinate very nicely. Why change?

I'd like to see a larger picture of the kitchen, but I think we have a tile that would possibly work well with your counters. It's called Liberty tile and it's unique to our company who handcrafts it. Here is a link- http://www.granitetransformations.com/southjersey/products/mosaic-tiles/colors/liberty/

Those counters are pretty busy, so I'd go with something that can create a stable focal point.