I would do gray walls and just make sure it has the same undertone as the tile I often paint the ceiling the same as the walls if going with a light color or if a little darker for walls I cut wall color 50% for the ceiling. I have a gray and mostly white LR and I have walls a color called Vancouver Day from C2 I then add color for different times of the year with pillows and a few accessories The wall behind the sofas I just painted in a purple from one of the pieces of art and I love it.

I love dark shades but from my experience oil stains on a dark shaded cabinets in kitchen specifically are more prominent.

I am assuming you haven't finalised your wall colours and colours of any other fixed elements. In case you have finalised your color scheme you would need to see which of these colours blend well or complement with that scheme. Assuming none of this info is available, then you could look at the neutrals which go with all colours. The white tile and the 2 colours at the end would be preferable. If you want color on the floor as well as drama, you can choose from the 2nd options from both sides or even the 1st from left.

Kelly, if you would want it to appear in the center, you may have to add a mirror half way up on the left wall. Adding long barn shelves on the back side will add to the centered look. The shelves should touch the mirror for a seamless look. Back wall can be spruced up with handmade tiles. Thanks, Nitin Cornerstone Designs