I think it will look a bit fragmented if you stop at the cupboards. lovely kitchen and the sign is amusing :)

Or what tiles are they? Even the whole wall may work and nicely zone the kitchen

Thanks for your comment. Quite big. 15x40 in a bricked pattern. They are very light glossy grey.

Was going to say all the way. C's mock ups confirm that, I feel.

Nice tiles too!

Do you mean like this @Daza? (do not mind the gap, I'm not the best tiler in the world ;-) )

Yes I was thinking a shelf or two also. Thank you.

Here's a mockup of tiles up to the top of the white cupboards. Hope it all helps to make a decision.

I think all the mock ups work. I'd probably go for all the way along the worktop, or all the way up to the dark units (on the left).

And I might go with these tiles. They're great.

I would go all the way along the worktop, up to the underside of the white cabinets. I'd keep the sign. Wouldn't add shelves. But I would think about adding a more substantial shelving unit/cabinet on the right side of the kitchen, where the small wooden cabinet now is.

If you look at Carolina's mock up above and compare it to the original photo, that back wall looks so much better a darker tone (even light grey tiles will darken it). I would consider painting the unit walls a darker tone to match the tiles and create a bit of depth, right up to the ceiling.

Appleoz gorgeous kitchen, I think I am with Colour Happy here, a darker colour on that whole wall would ground that wall and you wouldn't need need any tiles. Paint is so much cheaper and easy to re touch as needed. I am over trying to keep the grout lines fresh and clean..

By the way I love your floor can you please share a source??