Can you share some photos with the options you're trying to pick from? Narrowing it down for us will help you get more valuable feedback.

Suggest a marble (in whatever shape you prefer) that ties together your choices.

With all that white I'd want color. For myself I'd go bold, but a soft celery green subway tile might be more generally appealing.

Uploaded photos with some tile options we are trying to pick from. Could you please help to choose? cc: @Amanda Healey

Because you have marble on the countertop, I'd let that shine and use a solid colour in the backsplash. You don't want to be competing or too matchy matchy in my opinion. Let each surface be it's own thing and not blend into each other. The classic option would be the white. It won't ever look dated and you'll never need to switch it out. I'd go with the medium sized option in the classic offset horizontal pattern. I think the biggest size might make the space look smaller, or a bit messy because you'd need to trim them so much, especially to fit under the window. You could also do a herringbone pattern with the smaller size if you wanted a little extra pizzazz.

I can only say that I notice the amount of drawers, and each with trim, making slightly 'busy' look already.