Are you talking about the wall that is currently white? I'd leave it. Once you have everything including yourselves in the room it won't feel boring. You can add art, as suggested, as you find it. Plain spaces are needed in rooms to allow your eyes to rest and for the other features to be, well, features.

One thing you might want to consider too is the finish of the bench top. Even though dark colours absorb light if you have a shiny coating on your bench top it might give you that glare effect. We have a dark green laminated bench top. And we get a lot on sun in the morning and the bench top is quite resonates a lot of glare. Opt for a matt finish in a material that won't throw a lot of light back. I have attached a photo of our bench top to give you an idea of what I mean

I'd start saving some inspo pics here on Houzz so you can see the common threads of what you like. Then I'd pay a few hundred dollars to have a design consultation. In your area you will have a range of choices.

You didn't mention the face-brick wall that is a real feature of this room. If you are keeping this brick wall as it is I would go with a plain white benchtop, as a marble will be lost with the face brickwork and feature timber. I think that you are on the right track with the grey floor tiles, however a bluestone grey is a cool grey, and you have a lot of warmth in the brickwork and timber. I would suggest a plain warm grey tile, with a hint of brown , perhaps similar to the mortar colour in your brickwork would complement the rest of the room quite nicely.This is a render of one of my current jobs with a similar scheme to your proposed white and timber which works quite nicely for the 1970's home that it is in. Best of luck with your kitchen renovation, Dr Retro of Dr Retro House Calls