I agree to something plain but you can jazz it up with installing a unique shape or pattern. What are your counters? I’m looking for a similar look for my master bath.

What a charming house! You've done great. I had somehow missed this thread up to this point, and I did not read all (or even a significant fraction) of the previous responses. I have a 1910 house and also don't like subway tile. But I wanted something that fit the era of the house. I ended up going with a simple (and extremely cheap) 4x4 white field tile capped with a contoured molding tile (that almost but doesn't quite match the field tile because I couldn't find a molding I like from the a manufacturer that did a 4x4 field tile that was 4x4 rather than 4.25 x 4.25. Adds to the charm). I have very few uppers, though. I think a 4x4 white (or gray, since you seem to think white is too stark) field tile with black or charcoal pencil liner would be cool. These all show a pencil liner with subway because that's what the popular kids are doing, but it would work as well with a 4x4 or other basic field tile.

A white or grey tile might work well with your countertop and other selections. Here are some images from our kitchen designs we have done over the years that might aid you further.

Your granite is stunning and is much more attractive with your cabinets than pulling the short splash and swathing the wall in white tile. That will just introduce a competing pattern with the grout lines. Leave it as is. Here is a recent thread on your current counter/short backsplash combo that you may like. If you need something behind your range, have a piece of your granite fabricated slightly taller, or use a piece of stainless, or in this thread, I posted a photo where they used small, square, blending tiles behind their range only: https://www.houzz.com/discussions/6246858/is-the-short-3-6-kitchen-backsplash-coming-back-around I agree with @cit3 that your floor should be more uniform. I'd go less red, as well. I've seen your floor choice with dark cabinets, but those kitchens had more muted counters. I think less dramatic floors will give your eyes the proverbial "place to rest".