I recently realized this when we were remodelling bathroom and kitchen. After viewing a lot of photos here at LikePoint, I realized this:
a. Smaller the tile size, location looks small. Probably, that is the reason why kitchen countertop tiles were once small compared to the flooring tiles - it would make the kitchen floor look large.
b. Larger the tile, location looks large. However, because of the structural strength, I would not recommend tiles larger than 18-20 inches.