What about the rest of the room and ALL the other finishes? Surrounding rooms? Other things going in the bathroom? Size of the room, post a floor plan with dimensions? Natural light? A complete room design is a combination of all the items in it. Context is key.

IMO a spa look is light and airy so dark and moody noyt in my head. I hate too many grout lines in any shower and the fewer tiles style and colors the better . I do not think either of those choices say spa to me . I like all 12 x24 tile on bathroom floor and shower walls the same tile only smaller for the shower floor , matching grout , stacked pattern so nice and simple as a backdrop for some nice wall color and the bility to change the wall color and accessories when ever .I have no idea how the inspiration pic is anywhere being considered in the choices you posted. So if a darker palette then something like this is what I mean for tile and the same for the floors a bit darker like you are wanting but still tranquil like a spa