I would have to agree with your husband that a white glass tile would look best here - however, a light cream color may give the kitchen the little pop of color it needs without being too bold.

The gray tile pictured could be a good fit as well if you want to add in some under cabinet lighting to brighten it up.

Here is link to our cream, this is a really subtle color and would match very well.

3"x6" Cream Glass Subway Tile · More Info

If you are looking for a lighter gray that will keep the area light and add a nice contrast to your kitchen, we have a blue-gray called "cadet gray". Here is the link to that:

3"x6" Cadet Gray Glass Subway Tile · More Info

These can all be found in our Houzz store along with quite a few other colors. If you would like to see any of these in person just let me know and I will send out some free samples for you!

White would look good but not the only good option.

Don't add in a few gray tiles to any color. That will be just the sort of thing that will date your tiles.

These tiles laid in a zig zag would work with the counter and the cabinets. They look sleek and modern but not over-the-top.

Here's a gray herringbone that looks pretty great.

And one more done with two colors or tile

These could probably be found on line. They can also be found at large stores like The Tile Store. They might actually come in 12 inch sheets already cut and laid in the pattern.

My advice would be to go with the same pattern of backsplash everywhere. Don't try to mix in a different medallion over the stove. It is going to date your tiles and break up the sleek lines. Those tiles above are pretty but also dark and busy. Remember the Tuscan scenes that were popular back in the early 90's? Err on the side of simplicity. You can always add some bling in accessories and thing that aren't permanent.

The cream is very subtle and would look fine with the white sink and table. Your walls and counters are already a gray color so you don't want to add in any more darks into your kitchen. White or cream is definitely the way to go with this project. I wouldn't recommend using something different over the stove, keep it consistent. If you'd like those samples just contact me on our Houzz Profile.

I love leelee's herringbone suggestion. Beautiful tiles.

This was the closest thing I could find. I'll browse around and see if I can find anything closer.

[https://www.houzz.com/photos/bryn-mawr-residence-traditional-kitchen-philadelphia-phvw-vp~859521[(https://www.houzz.com/photos/bryn-mawr-residence-traditional-kitchen-philadelphia-phvw-vp~859521)

I photoshopped this for you.. this was taken from a kitchen with yellow lighting so the cream color is a lot more intense in the photo then it would be in real life (you'll see what I mean when you get the samples) but this at least gives you a decent idea.

The link I provided above gives a pretty good idea of what the cream looks like in natural lighting.

I wasn't able to find any photos with the gray that had a similar layout to use in photoshop unfortunately. Sorry, I hope that i've helped make your decision a little easier!

Unsanded grout comes in all kinds of shades and matching it should be pretty easy. I would recommend getting the subway tiles installed first, then trying a test area with the gray grout to make sure you like it. If you don't like it on the small test area just hurry and clean the grout lines out and repeat until you find a color you like. I wouldn't recommend doing different color subway tiles on the opposing walls, I think its better to stay consistent.

I would love to know how you like the Caesarstone Sleek Concrete 4003. I considering it for my bathroom vanity.