Well, you could certainly provide some counter height stools without adding onto the counter. I would make the stools simple ones that don't call attention to themselves. Look at how the ones below are there to be sat upon but there's no overhang. The height you will need is called a counter stool. Or you have space for 2 at each end of the island with just a big of an overhang. People just like a place to perch while they chat with you while you're cooking. White stools would blend right into the island and be inconspicuous.

I love the tall units but you need to go straight to the ceiling to prevent dust and dirt settling on the top. I would put a row of small up and over cupboards along the very top as an option. Very handy for unsightly bulky items. I don't like the end open shelves by sink very dated but what you could do is a long double shelf all the way along the island with a wine racking either side for balance vertically. I think shelving each side of the sink would be better. You have a lot of cupboards but no deep drawers which are highly valued these days. Good selling point. I Like your colour suggestions... The little Greene paint company have a lovely grey so does farrow and ball. Where are you sourcing your Quartz and what flooring? Do your ovens have easy open shelf doors ..handy as they retract so don't get in the way as you take food out..Neff offer best ones. If you want a better balance of tall you could always do fridge freezer one side and pull out pantry on the other with racking. Then on sink side don't go all the way along the wall just have it as centred space so you can pull out larder doors. On your island you will need your bin as this'll be prep area? What is the room opposite tall cupboards? Need the island to look good from that side as that is what you will see. Hope of help. I'm embarking on the same thing and have spent hours and hours researching!

We are about to put in a new kitchen with an island. We really like the idea of a raised bar/overhang with a wooden effect but don't want the care involved in real wood. The guy putting in my kitchen is advising that the laminate might cheapen the kitchen. Can anyone help? I've seen it in a few showrooms and do think it can work. Thanks.

Would suggest white! A warm white like wimbourne white. All of the most beautiful rooms in my house are painted white! Then add in some wall art and some plants.