I would use the same tile as on the floor , if you are wondering what layout will look best draw the shower walls to scale and draw the tile to scale on the walls I like a stacked tile pattern in small spaces so try that first. IMO if you do a stacked pattern that tiny bit of trim off the tile will be barely noticeable at all.Make sure the full size tiles are in the corner you will see first.

I personally really dislike large format tiles on a shower floor. The lack of grout lines make it more slippery. That might just be me though.