I too had a hard time choosing whether they should be the same or just coordinated. I ended up using different sizes and patterns in the shower and floor because it allowed both DH and I to use our first choice tiles. We used large wall tiles in the shower and 6 x24 on the floor both with thin grout lines. Even though I went in a different direction, I feel bathrooms are places where matchy matchy is a very serene and lovely look.

I looked at 24x24 tiles in the store and they were HUGE! So we did the same 12x24 on the shower walls, around the tub and on the bathroom floor. then used the same tile in mosaic for the shower floor.

Like Roarah but opposite. I went match matchy even though my tiles are busy because I wanted a more serene look, but i love when people do coordinating tiles are not the same if it is done well, it looks very unique and skilled.

I have a whitish porcelain, marble look alike, on the walls. A very darkish highly variegated tile on the floor. I have a light gray Kohler cast iron shower pan. Its the sample chip setting on the "marble" tile. When I pulled the two tiles together at the tile place, the sales lady looked at me funny, lol. I loved the look! So I went with it.

This is a planning stage photo, when I was picking out my shower pan. My "marble" tile is more variegated than this image shows. It wasn't the brand of "marble" I went with.

Here is the "marble" tile I went with (not the other tile, but similar), in the 12x24 format: