I prefer the large format tile. I would place it on a diagonal to broaden the floor space visually. Is your floor exactly 9x13. If it's a bit smaller, you could work with full tile and full "half" tile cuts. If the room is a bit larger, then on two of the walls, place the small triangular cuts under the tub and behind vanity/toilet. Since I don't know your fixture layout, I'm making certain assumptions. If you install the tile square to the walls, you have obvious cuts that can work against the large format approach if using one type of tile.

A larger format, even in a small room, can help it feel expanded. Just make sure your subfloor is absolutely flat, or it will be impossible to lay the tile without bad lipping.

Also, make sure the tile is not too slippery. With fewer grout lines for traction, you want to make sure you're not sliding when you get out of the shower.