Here are closer views of the marble and aluminum options.
Thanks in advance. . .

Yeah, The "pattern" on the marble is small, so for the tile, I'd go with a pattern that's medium or large.

Keep your backsplash very simple and a neutral even color. Look on houzz at examples of backsplash designs. I think you will see that the very simple designs look best.

Here is a better picture of split-face mosaic tile and a glass subway tile and a marble subway tile. The painted board will be the color of the cabinets.

I like the ivory mosaic because it is the most simple.

Can I ask what the island gray blue paint color is? I am looking for a color for my living room fireplace wall and that is perfect.

Rule of thumb with remodeling kitchens. Select the feature that you want to wow everyone. In your case the lovely granite. Don't get a small busy backsplash that competes with your granite. Keep it simple. Glass tiles add some depth to an otherwise flat wall. Also, is it too late to remove that granite that is on the walls? Now the backsplash goes all the way down to the countertops and looks more expensive. Careful not to go too dark on your backsplash. Also, remember to put up strip LED under cabinet lights. Question, why are you painting the back cabinets? I love the blue island with the brown ones in the back. Look up luxury kitchens and take a look.

You like tile with visual interest but we are recommending neutral. Hope these bridge the gap. I also like the current cabinets- not painted - with blue island!

The island paint color is Storm Cloud by Sherwin Williams.
I love the geometric type backsplash. . .a bianco arabesque was my first choice - but didn't know how to finish the top near the window and the side adjacent the dining area.
Right now, i'm debating between a whitish glass tile and a honed carrara marble tile, with a strip of the marble mosaic one tile up.
Haven't ever loved the dark cabinets - more of an eggplant color while the counters have true black in them. But after doing the backsplash will make the final decision.
Also, the kitchen is very dark; the blue cabinets will lighten it up.
The glass tile would be very similar to the current wall color, but the grout will make a difference.
Thanks to all of you for your suggestions. Will consider removing the existing short backsplash.

Several views - glass tile on left, then polished marble and honed marble. Thinking the polished is too "elegant" for my more casual preference. Also, shiny.
And, BTW, got the idea for the storm cloud paint from a story on Houzz.