I did Travertine tiles in my master bath and went with Travertine countertop - I love it! It looks so uniform, pretty, and serene. It looks nice also because you have a counter of 4-5" over the wall tiles, and if the tiles and countertop are the same it kind of looks uniform and consistent. Here is a link that might be useful:

I am a fabricator. "Quartzite is a natural stone but much more easy to work with than marble, for example." This is a profoundly incorrect statement. Quartzite (real quartzite, not the various marbles sold as "soft quartzite") is a real challenge to fabricate because it is so hard. It processes much more slowly than most stones and wears out expensive diamond tooling several times faster than typical stones. A $3500 set of diamond CNC router tools will last for 20-30 jobs on typical stone. Quartzite can wear out a set of tools on a single job. This hardness makes it a more durable than average countertop. Conversely, most marbles are a joy to fabricate. Easy to cut and easy to polish. The disadvantage of marble is it's porosity and softness which make it a much less durable surface.

We used BM White Dove In different sheens on the walls and woodwork to complement the polished TM Counters (but we have natural wood cabs). Our kitchen has north facing windows with lots of green trees. We compensated for the low light with 3000K (the warm-ish colored not the blue-ish colored) LED undercab and in cab lighting and sconces etc. The updated kitchen doesn’t seem dark or gray now which I was concerned about. I would definitely wait until you have the cabs installed, the counter in and some of the lighting wired in before choosing the backsplash. I was very surprised at how my original white tile choices didn’t do a thing for my counters and cabinets. good luck!

that subway tile is too creamy yellow. Taj is a cooler toned stone. more grays and cooler whites. I wouldn't use anything yellow based. These do not really go together. for sure the yellow/peach tile doesn't I personally think the "travertine-look" larger tile is too busy, will compete w/both flooring and the Taj, and quite frankly has had it's day. I'd do something like this,, any of these look great w/taj. the mosaics would work on the shower floor and the niche or accent. or, look at these for larger tiles for either your bathroom floor, or even the shower walls. 16x16 Terrazzo kashmir,, next one is Tilebar, 24x24 porcelain, matte limestone-look. (I love that tile) Tilebar Cavatina is also nice. these come in a 12x24 size too. I'd use this or the one above, over that other tile you picked. (ignore the decorative tile) Do a 3x12 or 4x12 subway tile set in a stacked pattern. Or this tile in a white or soft gray, also in this same layout. are you dead set on the wood look tile in the bathroom? is this a rustic house? is this the look you want w/your tile in the shower and the wood look tile? I would use a solid porcelain tile for the bathroom floor, maybe in a herringbone. a darker, warmer gray would look nice. (or a soft white) Or, this herringbone below would look killer on the floor, or even in the shower. Finland White wood tile at Floor and Decor. that wood look tile looks nice in a bathroom that has more of a country feel. is your bathroom country style? I'd say no based on the style of that traditional vanity. the two styles clash. as do the different larger tiles you've chosen. A Zellige tile would look amazing w/the Taj. it's here on the floor. and doing a busy mosaic pattern inside of a busy larger tile, just looks busy. especially with all of the other busy tile (floors and countertop) you have. Look at Cloe tile. they have a soft gray or a white that would be perfect w/Taj. Diff sizes and shapes too what if you got Taj Majal tiles? You don't have to go to this extent, but they'd look nice on the floor or in the shower taj countertop, lighter, creamier/gray flooring