you need to post a picture of the kitchen.

I added a photo of the kitchen, but it will end up much different that what is shown. New shape of island, hardwood flooring instead of tile, and cabinet color will be off-white.

Thank you. That is good advice

when you say off-white, what were you thinking?

you have to be careful because you could end up w/something looking very yellow.

why not get a sample painted on a few of the doors?

Try Simply White. it's a warmer neutral w/o being overly yellow.

So, matching the cotton granite. honestly, you're going to have to buy a full slab, so why not just use that slab for everything else? you don't have that much of the cotton white to salavage on the other countertops, I'd just scrap those.

your island isn't a traditional looking island where you can get away w/using a diff countertop. It looks more like an extension of the other countertops, with gaps in between, if that makes sense.

Find out how much you need for your island and see how much of the slab is left over. if there is enough, do the other part.

other options-you could opt to do a butcher block or even a honed black granite or suede quartz.

or something like this white quartz.

here's a two tone countertop option before/after

they lowered this one too and used a diff granite:

https://bella-tucker.com/2017/10/two-tier-kitchen-island-update/

as for the island, how large of an overhang will you have?

something like this?

This?

For sure I'd advise you to finish off those end panels around the island for a more finished look

see how this one added simple batten pieces and a baseboard? ^

many ways to do it. get some simple MDF trim pieces

see the before/after in these two?

Or do something like this before/after

Beth H., this was incredibly helpful. I really appreciate your links and photos. Very helpful!

"Do I need to replace all countertops in the whole kitchen?"

No. I needed material from a woman's island to be able to replace her kitchen sink. She replaced it with a solid black, her estone top had black particulates, and it looked like she had planned it that way.

Had another this month that replaced her island with butcher block so I could install an apron front Kohler Whitehaven with a remnant. She didn't need to; I just needed some overhang off one end.