I hate trying to get wall and floor grout lines to match up, mainly because the corners on walls then look all wrong to me. I try to give the illusion of a full tile round a corner, which means that you can't get the floor to match in both x and y plains

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I usually tile the walls first because there's always some wall adhesive and grout that seems to find it's way onto the floor no matter how many dust sheets you put down. I then talk the customer into a diamond pattern on the floor which, IMO, looks better anyway.