i love the grey, very fresh and clean, the tan looks outdated.

Neither. Think white sand beach.

I think both the grey and the sand coloured tiles you've picked are quite busy combined with the granite and the wood pattern. Hmm... I would try to find something with less 'movement'.

The grey. I did this same tile in a bathroom and it looks great. Since it has both tans and greys in it either work, but the grey works better with the top.

the grey tile. if you want to use the Sandy beige tile, you might consider Labrador Antique instead of the granite that you have selected. in my opinion, the beige tile goes better with the rustic wood floor tile. of course it could just be the way that it appears in the image. I used Labrador Antigue granite on my counters, blacksplash, tub overlay, bench, floors, door jams, and some some accent points with Crema Europa limestone as the field tile. See Pictures. For smaller bathrooms, i like it when people limit the number of materials used.