Tall units up to the ceiling can look very nice, although would function as displays mostly. Honestly standard height kitchen wall units wouldn't concern me, they might accentuate the height which is not a bad thing at all. Alternatively if you have enough storage in the base units why not skip wall units altogether? Open shelves or even nothing, just a stunning splashback

You're the customer so have it how you want. Its more expensive to tile wall to wall which is why lots of kitchens are only tiled up to the legs, but its getting more and more popular to have the kitchen fully tiled before fitting like they do on the continent. When we have a kitchen to fit and its been tiled we lay hardboard over the floor to protect it, so it is an extra small cost. Accidents can happen though like dropping the oven but that could of been an old existing tiled floor that could be chipped and no replacement tiles available. Also its harder for your fitter to install as he has to scribe and seal all your decor panels to the floor when its been tiled is another reason installers prefer it to be tiled afterwards.

We have a wood effect carcass. They’ve been in for 15 years and barely have a mark on them. By contrast I removed the white carcasses in the utility room - after about 7/8 years they were marked and the edges looks a bit grubby. We have replaced them with ceiling to floor hand built cupboards for the washer, dryer, etc. The wood effect carcasses in the kitchen we’re not visible but the original doors of our kitchen were fitted well. We’ve now replaced the doors and kept the carcasses as they were so good!

Aqua would look amazing with a white kitchen, but I think an off white would go beautifully with midnight blue. Something like F&B All White. I think Slaked Lime by Little Green would also go nicely too. My sister has a charcoal-navy kitchen and she chose the palest of greys and it does look good. The last picture shows Slaked Lime with navy.