But for the floor, you have just described my bathroom. I used RH Silver Sage mixed by Sherwin Williams. It looks very calm and soothing. I get lots of compliments on it .

If it were my room I think I would go with gray owl, that one being the lightest of them all with not much undertones
I think horizon has a green undertone and smoke embers might be a tad dark with no windows.

If you have any leftover tile I would take a piece in to a paint store and have the consultant help you find a light grey that matches the tile. You don't want to choose something with the wrong undertone.

Colors look very different with no natural sunlight. You should paint a largish piece of poster paper in each color you're considering and hand them o. The walls. Don't view it horizontally on the floor next to the tile, hang it up, because colors appear much lighter on the floor than on the wall.

The colors in my windowless bathrooms are similar - except the floors are white, the vanities are cherry (tops are white) and the tile in the shower is glossy (also porcelanosa). We used a silvery blue that I love (picture attached), but. I don't remember the name - if you're interested, I'll try to find it.

I love gray owl-- but I disagree with the poster who said it has no undertones. I have it in my bedroom and LOVE it. It is fresh and clean and very relaxing but it definitely has has a blue-green tone in my room. Beekeeperswife has gray owl in her home and in her space it does read much more neutral but every bit as fresh and clean. I recommend that you do as KSWL suggests-- test your paint samples on a poster board and check them in your room with your finishes.

Just wanted to say thanks to all who responded. I appreciate your suggestions. Will be taking my floor tile to the store. I will try to post some pictures when done. Much appreciated.

Gray owl does have a green undertone to it