I don't know if the carrara would look odd. that really would be your call. we did a slate floor and white subway tile walls with some accent strips. In the shoewr we tiled to the ceiling with the subway and did the ceiling in subway. or more correctly, we picked it out and my tile contractor did the tiling. I think it looks good that way.

We went to the ceiling. Measure and figure out the tile layout in advance to make sure you don't end up with small cuts. Don't rely on your tile guy to do it. Attached are pictures of our shower. The tile guy wanted to do two full tiles in the center of the back wall and then small cuts on the end. I pointed out that if you did one full in the center than the two on the end were practically full size. We also made sure to cut the ones for the shelf in such a way that the lines lined up with the back wall. The small cuts were down close to the floor and less noticeable than they would be on the top row. We also used floor tiles. I took them to a custom bullnose place. It was $100 to bullnose enough for the wall edges and the shelf. I liked that better than the plastic strips that are often used to edge the tile. I got redundant bullnose pieces for the unique pieces on the shelf and a couple more redundant pieces for the edges just in case of a bad cut. But the bullnose people messed up, not realizing these were redundant pieces and I had wrong bullnose edges for the redundant corner piece. Luckily that cut went well so I didn't have to go back and get another piece made. We also did full size tile at the edges of the sides and the cuts are toward the back wall. We used color matched silicone caulk in the corners and on edges of the shelf. White paintable caulk was used on the ceiling and adjacent to walls and white silicone caulk adjacent to tub. So three types of caulk used. There are small pieces at the base near the floor but you don't see them unless you are looking for them. He made all but one cut well. The bad cut (too wide) was on the shelf so I didn't spot it before it was put in. I checked on him periodically and the cuts were so precise that I wasn't checking after every cut after a while. The shelf was one of the last cuts. I had let my guard down by then so he did sneak one bad cut by me. The radius cuts around the tub were excellent. He did the cuts against the ceiling very nicely because of course everything wasn't square so although they are all flush with the ceiling they had to be custom measured with each cut to insure such a good looking clean line on the top. He washed the grout out with too much water when cleaning up, leaving the grout very white so I put a color enhancing seal on. The grout lines mostly disappeared with the enhancing seal but it left them shaded irregularly. It goes well enough with the tile so I didn't worry about it. Overall fairly pleased considering some of the jobs on here. His caulk lines are good but I insisted he use tape with the white caulk after seeing him not use tape with the color matched caulk. He did one very weird thing. He was worried the grout would stick to the bullnose edges so only grouted up to about an inch away from them. He was planning to caulk those edges in. The caulk was not that well color matched so I tested the grout on the bullnose edges and it did not stick so I had him go back with a second batch and grout in all the places he left empty. You can see in the pictures where one inch from all the edges is a slightly darker grout and sometimes not the same level. There wasn't much I could do about it after it was done other than have him fix it the way he did. Luckily it isn't that noticeable.

For the tub/shower area: Tiling to the ceiling is a nice clean look. This is what we did in our recent remodel of 2 tub/shower combos and 1 tub to shower conversion. The only negative IMO is that it can present a challenge to the tiler if the ceiling is not flat and the tiler is not skilled enough. My tile pro made sure the ceiling was perfectly flat. Be sure your tile pro does that. You don't want ugly slivers or other unpleasant errors where the shower wall meets the ceiling. For the other walls: IMO in looks most lovely when you tile all the way to the ceiling in the shower area, and then you drop it down and do a tile wainscot for the adjacent areas. That way you get a little bit of wall area in the bathroom that you can paint a subtle/soft color, or a bold/adventurous color, rather than having tile absolutely everywhere. Here are a few HOUZZ photos showing this:

That's often true, Melissa, but it would be a shame if someone paying full price for a brand-new shower installation didn't get the benefit of modern waterproofing technology. I say this partially because we are currently remodeling a probably 25-year-old tile-directly-on-drywall shower and the entire other side, the bedroom wall behind it, will also have to replaced due to the amount of mold we've found. (Particularly expensive and frustrating because it's a historical house and the walls are lath and plaster.) The mold is really disgusting and I wonder of some of our recent health issues could be traced to it. Blechh. :/