We have distressed oak flooring that we love. We didn't pick a color until right before it was ready to be stained. The walls and cabinets were already painted and stained. Our guys came in with a selection of colors and stained a few blocks on the floor so we could see the color in contrast to the other colors. I don't have time to post a picture right now, but my colors wouldn't work with your colors anyway. Does your builder have someone who can help with color? My builder had a good eye for color and helped direct me to good choices. I found the paint and stain guys to be pretty helpful too. Good luck on your selection.

Sorry for your troubles; it's impressive that you're getting this done so quickly.. That tile looks like it coordinates really well with your entry tile and the stairway. It's not too dark; I think a lighter color would make the existing tile stand out too much. This choice would look great, especially since you say you get a lot of light. It's got a lot of depth in the light.

That is a truly beautiful and elegant kitchen. i can see why you'd want to replace the backsplash. I think you'd tire less of the lighter tile in the long run. For starters on the lighting, I'd check anything by Visual Comfort & Co from Circa Lighting. The light quality from those lights is superb. Also take a look at the modern designs from Hinkley Lighting. On your floor, you might consider a product like Loba's 2K Invisible Protect or Loba 2K Supra A.T. without a stain. White oak in lighter tones is very popular right now without any stain. Here's a video showing how Loba products prevent tannin pull in white oak when applied correctly: https://www.youtube.com/watch?v=Kbu7kCzd1P0

I'd not put the matchy-not-matchy floor with the wallpaper. It's easier to style with wall paper that can reasonably be changed, tile floors are for the long term. I think a neutral floor can work for decades - or a timeless black and white. (The pink and metallic gold tile my parents chose for their small bath in 1972 looks pretty awful now, but the bathroom with the plain white 4" squares is fine.) Tiny tiles mean more grout and more cleaning over time.