I'm not a big fan of large format tiles, but in a large room with flat floors they can work well. The tiles above are 60cm x 60cm Porcelain with a polished finish. I fitted these in a customers kitchen and finished with a white grout
At the other extreme I have recently laid these 2.5cm mosaic tiles in a bathroom. To make the room look bigger the tiles were continued to create a bath panel. With lots of grout to potentially get dirty I always recommend a non white colour.