I have a similar tile in my master bathroom. We went with Tec Silverado.

Whatever you choose, do a test board with the tile you have purchased, the grout you think will work and a grout color that is a shade darker. The tile delivered to me was slightly darker than the sample tile, and grout dried lighter than the shade on the paper chart. Don't make my mistake!

Do you know what the polished grey square tiles are in the photo or where I may be able to get these? Thanks!