About to tile a rectangular walk-in shower that is 4’x5’feet (other walls will be pony wall/glass). Will use white subway tiles, light gray grout. But can’t decide what subway size will be most appropriate for our space. Transitional design. I’ve had one designer recommend very large tiles (8x16?) and another recommended 4x10 or 4x12. There are just so many choices and I can’t tell what will be the best proportionally. Is there any type of design guideline that would help me make this call? I do want to see grout lines, but I don’t want to be overwhelmed with grout!