I need to order tile for my shower walls (like right now). I have a choice of 12x12, 16x16 or 18x18.

Less grout is always better, right? But what about the idea that it might be easier to work with 12x12. Because my shower has two walls and they are both about 48" wide. Using four 12"x12" tiles would look better than using 2.6 tiles across, right?

It's a honed and filled travertine. The floor is 2"x2" tumbled.