I would use a very pretty vinyl coated wallpaper on those two walls. I agree with reluctance to tile the whole room or two complete walls opposite to each other. We have a somewhat similar though larger room and we had tiled the shower then used a compatible tile from same group above the vanity…but not the rest of the wall. The toilet is semi enclosed and walls are not tiled.

Photos…. Note the tile is limited to shower and above vanity. The toilet which you cannot see is opposite the vanity and has only painted walls.

Not enough context to answer the question

Is the bathroom a gut? What is the tile? What is the floor, ie tile matches shower walls or is different ? Is the vanity changing?

What is the new vanity style if such a gut? What is your inspo, for a look/feel in the bathroom?

From what you have shown I see no reason to tile ANYTHING beyond the shower itself.

Come back with more context to your question, please?

this bathroom has 42” tile wall wrapping around bathroom thus allowing 7.8” backslash above vanity. same tile surrounds shower unit. gloss finish was used for walls n shower unit. same tile in matte finish was used for floor. In a smaller bathroom, this makes for a streamlined, clean look and easy maintenance. Id suggest doing same with your bathroom which appears to be a smaller room

You are paying the designer to consult and offer options ... and not to force you to do it a certain way. Be careful of a designer that wants you to use a certain product or do something a certain way, because they need different photos for their website gallery!

In my showers I also like to tile the shower ceiling. Lots of ways of doing things!

I don't have a good finished photo, but here is one of the tiled shower ceilings in one of the secondary bathrooms in my previous house.

IMO all tiled bathrooms remind me of school showers not a nice home I like 12 x24 tile porcelain ideally for both shower walls and bathroom floor then just a smaller version for the shower floor. If you want a bit of accent the ideal place is the backsplash for the vanity , when you tire of that it is easily changed . If you want a bit more use wallpaper it again can be removed and changed. The simpler you keep the major finishes the longer you will like the space .A simple all one color tile allows you to change wall color accessories with little expense . Yes tile to the shower ceiling and most important the venting is up to par.