I agree with you. Tile up to the window only and only the back wall if using white,
Do you have a feature tile in bathroom or is it fully tiled in white? You could use feature tile or run the floor tile up the wall instead. As a feature.

i wonder about the fashion to tile whole bathrooms and powder rooms..what do they expect to be happening in the room to need so much tiled walls and all that extra labour adds so much to the overall cost let alone the cost of the extra tiles and where better to add some adventurous colour or artwork ..the unfinished look can be overcome by adding metal tile edges or laying the tile in a pattern to frame the rear wall

A suggestion/idea

The majority of separate toilets tend to look ?

Dependant on floor tile colour.

Floor tiles up the rear wall to cornice , tile window reveals

Skirting tiles, floor tiles (if 300 x 300 half floor tile or 150 mm high

Separate toilets tend to be too small for more than one tile.

White tiles up rear wall would require dark walls

We re taking oak coloured vinyl floor thru to the toilet .. thanks for all the advice and pics.. love the feature tiles but don’t want to go to too much expense .. will just use our white wall tiles as they were left over from the bathroom ..

Paint is inexpensive, very effective and easy to change, even though you have left over tiles it will cost for labour to lay them, perhap you would be better keeping that small amount for any possible accidents to the tiles in the bathroom

Suggest you tile on all 3 walls however just up to under the window, then paint the rest. Then you have some more continuity.

From our recent projects, we can see that fewer people are tiling or using the same material all over the walls in bathrooms.

Your options would be:

- Add similar coloured tile to the paint in the bathroom to only add texture while keeping the colour scheme the same.

- Or to Contrast and make either the paint stand out or the tile, like some of the photos you've attached.

- However the above two options are not relevant if the rest of your bathrooms are all tiled and therefore the guest bathroom might stand out or look very different to the rest of your home. In this case, you should listen to your tilers' advice.

From projects, we have been part of, it is all about consistency that makes space/design look seamless.