I see your post is from over a week ago, so maybe you've moved on since then but having spent lots of time researching bathroom tile recently and spending hours in showrooms, I've noticed that Carrara can be pretty grey. It seems to be more grey than white from what I've noticed. I agree that the chair rail does look whiter than the tile and that may not be the look you want. If you stay with the carrara perhaps you can find an alternative finish option.