You might be pleasantly surprised how different it will look when you change the wall colour. Perhaps if you didn't that first, you'd not need to change the grout. I'd agree; if the tiles aren't symmetrical then a darker grout line would highlight this. I'd also agree that dark grey would look great - you have this in your floor mats and it looks nice against your gorgeous floor tiles. We went grey in our ensuite. Hubby was concerned it would be dark, but we love it. Worst case - if you change your mind, paint is an easy swap. Good luck ;)

It comes down to personal taste doesn’t it? I prefer white tile with white grout as I think the grey grout has a grubbiness about it, rather like public toilets in the 1960’s and 70’s. Obviously if you are relatively young then you will not have this wonderful memory lol!

I haven't come across this brand but have you looked at moduleo luxury vinyl flooring... when I last checked, it had good reviews with prices cheaper than some of the karndean products.

Love arc3d’s picture! I can also see a New England look - traditional furniture in pale blues, creams and natural fibres. Something like this