I myself dislike dark bathrooms because it's harder to see where to clean and some things show up clearer on a dark surface anyway.

We need more details from you like Creativelychallenged said.

But one thing I noticed in what you've told us so far is "dark tile will be in shower only".

I wonder if you need something dark elsewhere in the room to balance it? If everything is light except for the dark cave of the shower it might not look so good?

Please let us know what you plan to do on the floor, walls & cabinet base?

Contrast on your counter top will be good, depends on the colour & tones you have going on with the dark tile in the shower and other areas. If you stick to the same tones you can be clever with colours by doing them in different shades. For example...A cool grey dark grey can work with a cool grey mid to light shade..yes you can have 3x depths of the same colour in the same space, bear in mind tone is key

This image shows what I mean...walls could be a light grey, the floor a mid grey then the shower is a dark grey.