For the floor, I would use Laticrete Natural Grey, #24 (or a like with another brand). Unclear about the "no grout lines" for the carrara. How do you have no grout?? If that feature accent is on the wall with the carrara, we would suggest in this case that those be grouted the same and would consider Laticrete Silver Shadow for the carrara and the feature as well. Your contractor can do a mock up with a few left over pieces of each prior to grouting. That way you can visualize it before it is installed.

A couple things I’d like to add. I put epoxy grout in both my bathroom remodels. It can leave a ting of shadow in marble because it soaks in the sides of the tile. You don’t want that area to have sealer on it though so the grout can make connection with the tile. You can barely see the bleed, but it’s there. I personally love it because it adds even more depth to the marble. Here is my slate floor in a light medium gray epoxy grout. It looks almost white in contrast to the black. That’s the trick to the eye. This floor is worn hard. Farmer husbands bathroom with bad shoes. I don’t fuss with this floor except may be once or twice a year, lol. And it’s not hard. I do know that there has been some slight staining near the sink where DH stands to wash up. But it’s slight. The last time I mopped this floor was several months ago. I just sweep it. It could use another mopping I see. The right half never gets walked on, the left is the main walking path into the room. I can see a slight darling. This shower shown below, with porcelain tile, has a narrow grout line. It is a very light epoxy where I combined 2 colors to get a slight off white. No mildew or mold accumulates because it gets wiped down after the showers are done for the day by the last user. Usually it’s just me. I have not washed the walls except 2 times early on 5 years ago, because I thought I should. It is a waste of time because of the daily wipe down with a large microfiber towel. I do spend time with the shower door sweeps from time to time because they will get mildewy. The floor is a cast iron shower pan and I do clean that as typical for cast iron, but because I’m usually the only one using it, that’s not often.

So, as several people have said, you don't use grout at the tub or floor/wall junction. That end wall tile around the rounded edge is really bad. They used a dull bit to cut (nibble) and it looks really amateurish. It's not really clear what's going on with the edge, but it doesn't look like a properly finished edge (with a bull-nose tile). There's obvious grout / adhesive left on the surface. I think they used sanded grout - and that's why it's so rough and not filling the voids properly. My guess... is that the overall issue is that these folks didn't know what they were doing -- which is likely a bigger problem than just the cosmetic issues. I think you will find problems with the waterproofing under the tile also.

@Amir Ali - I just wanted to post a comment in order to: 1. Let you know that I completely understand what you are going through right now. I have TWO FAILING slate floors that are part of current bathroom renovations. The master bathroom floor had not been grouted due to delays on his part. I discovered that some of the tiles were COMPLETELY LOOSE - and some sounded like they were only partially bonded to the floor. This floor is failing - and it has BARELY been walked on because the bathroom renovation basically stopped due to issues - bathroom isn’t usable so the only use has been when I’ve gone in there to take photos or measure something = maybe some tiles had been walked on four or five times before I started discovering the loose tiles. It is obvious that the tiles failed to bond to the floor - the mortar must have skinned over or something. I am NOT reinstalling the loose tiles. IMPORTANT - my former contractor does not fit the definition of what people here on Houzz love to refer to as a “hack” (at least not the actual business that I hired to do the work) - however, his employee clearly did not know what he was doing (or just didn’t care) - and that makes the owner of the business liable for this work. The business has hundreds of Google ratings (4.9/5), owner is a member of TCNA, I had several reviews from people I know (and trust), and I DID NOT JUST TAKE THE LOWEST BID - I am NOT a CHEAPSKATE. I am so tired of people AUTOMATICALLY blaming the homeowner when they have ZERO basis to do so. Making assumptions and basically telling homeowners that they are IDIOTS and CHEAP really makes me upset. Okay, I’m finished with my rant! 😂 The ”fix” is this: The ENTIRE floor is being torn apart. Not only is the tile being removed, the cbu will be taken out. New contractor assumes that he will also find that former contractor failed to add the required second layer of plywood in order to make sure that the substrate was prepared correctly in order to have a natural stone floor installed. Based upon the above issues, I investigated the slate floor that was installed in one of the other bathrooms back in April. I noticed a few grout issues - and as I went around knocking on each tile, the sound on many tiles indicates tiles that are only partially bonded. This is what the floor looks like from a standing position: And this is what it looks like when I realized that I needed to inspect it after the failure in other bathroom: I have cracks and broken spots of grout in many places. I also have some grout which is stuck on my tile because the contractor failed to seal the tile (as required) prior to grouting (I found this out later - I was in the hospital while this floor was being installed) and made promises over and over to come remedy the issue. So, this floor will also be ”fixed” in the same manner as the first one - I’m just waiting to have it ripped out until after the other bathroom is completely finished. 2. I also wanted to let you know that regardless of whether (i) you have a written contract, and (ii) that contracts specifically provides (or fails to provide) a five year (or however long) warranty period, you still have recourse against the contractor who installed your tile. Most states (probably all but I haven’t done research on this issue in every state) have enacted statutes that protect homeowners for this type of issue. In my jurisdiction, there are specific statutes that relate to home renovation projects - these statues require (among other things) that all work must be done in a good and workmanlike manner. Following industry standards, as well as manufacturer’s specifications, are part of this requirement. Also, the consumer protection act in my state also protects homeowners against contractors who perform shoddy work. I am 99% positive that your state will have some similar statutes. If you want to share your jurisdiction, I am happy to take a quick look in order to point you in the right direction. MANY jurisdictions require the homeowner to provide the contractor with notice and a right of remediation. Unless you follow the requirements of your particular statutes, you won’t be able to bring an action against your contractor to recover damages. FYI - my former contractor has chosen to ignore the notice I provided, so I then was free to hire another contractor to do the remediation work. My former contractor will owe me the money I have to spend to correct his failure to properly install my tile (which will greatly exceed what I paid him - removing tile + cbu + buying new material (including nice slate tile - because I didn’t purchase cheap slate tile for the the project initially). I am sorry that you’re going through this because it is NOT fun. I decided to consider myself “lucky” because he hadn’t yet installed this tile on my laundry floor! Hopefully, you won’t have water damage that will require even more remedial work in order to fix it.