Definitely put the sealer on it. Enhancing is a personal decision. If you have an extra piece, try it to see if you like the look. We sealed the travertine in the bathroom after it was installed. We have slate-looking porcelain tiles on the floor of our bathroom and the travertine on the tub surround. We used two different grouts - grey for the slate and a beige that blended with the travertine. Not sure if you can really see the grout color differences but this is what it looks like. It didn't photograph well but the floor grout is a light grey.

Hey there, I have the same granite and backsplash as you! You'll see my pictures on the thread bluekitobsessed was talking about, I'll add the link to it. I also used the natural gray grout because that's what was used on my floors (also slate) and I had a bunch left over. Just a tip...I sealed first, too...but needed to seal again after grouting as sponging off the excess grout also seemed to wash off most of the sealer, too. I used an enhancing sealer and it also darkened my grout so you might want to consider that if you think your grout is too light. I also agree with the other posters about the wallpaper being too busy with the tile. The green paint you have is lovely! Mine's the deep terra cotta colored kitchen. Good luck! You have great taste! LOL! Here is a link that might be useful: that other thread

I used a product made by Stone Specific. It is a stone enhancer and sealer. I applied it with a sponge, waited and then wiped with a clean rag. I have stone mosaic on my backsplash, and they still look brand new. Good luck.

I think they look exactly how they are supposed to look, it's stone, so you're not going to have even grout lines. My DH is learning to be a DIY'er, and while the projects we've worked on may not be "professional perfect", it brings great joy when I look at what we or he has accomplished. Just a word of wisdom, remodeling isn't easy, and no doubt there's probably something else your DH would like to be doing instead. Appreciate the effort, focus on the heart behind the job and not so much how wide the grout lines are.