You assess your lighting. And maybe change the bulbs. That can have a HUGE difference in how colors look. However, it's hard to go wrong with natural gray for any warm gray floor.

Thank you! I think natural gray it is. I like platinum for walls, but it is so cool, I am concerned. It seems oyster gray is a better match, but may be too beige? The paint will be BMJet Stream. Can go warm or cool. Your thoughts are most welcome!

Try a more neutral, less interesting gray. Tile store samples typically use a traditional plain gray grout and they always look great. Look at it under various lighting types, as that seems to be an ever evolving element these days.