We have designed both.....islands with and without sinks. It is really a matter of preferance.
I personally would prefer to have my main sink along the wall with the window with a small "vegetable sink" in the island. I do not like having a cooktop on the island..........However, we design for our Clients and what they want, so we have designed all kinds of islands....

A big pro of having the sink in the island is that the island usually faces the living area or barstools etc. so if you're preparing food you can face your guests. But a con for me is that in our house, dirty dishes always pile up near the sink, so there'd be no chance of maintaining that pristine island bench you see in the photos. Depends how clutter-free you'd like to keep it between meals, I guess.

I Dislike sinks in an island bench. If you're a bit of a messy washer upper like me water goes everywhere.

@jtennr,
I am some way off with a kitchen as we're still building but I decided to put my sink into my bench because it worked there for me.
I can see into my lounge, even watch tv and also look outside my lounge window into my back yard.
If I'm working on my island, I can look out my dining window into my front yard.
My kitchen is in the centre of my open plan, so I don't actually have a window right at my bench.
You need to draw up your proposed kitchen just basically on paper, make sure everything that is going to cross over into this new area has a spot or home, like an appliance cupboard for example, for the chip maker, or toaster, coffee machine if you like such a thing.
Remember storage for all things great and small including the plastic stuff with lids and the bulky casserole dishes, right down to that draw every kitchen has for a screwdriver, or masking tape, a few biro's or extra notepads etc...etc...
Work out what you might be looking at when you wash up for example, will it be a nice view???
I expect you will have a dishwasher so the wash up tends to be more, washing hands, or rinsing the lettuce etc... whilst preparing and where do you feel you want to be doing that as compared to the rest of your open plan???
Your prep area should be close to the sink and fridge, as most things come from the fridge and you don't want to be walking a long way with a hanfull of food.
I drew up a plan and placed every single item into a location and made sure I had room for everything and almost forgot the microwave, such a big item too!!!
Best advice is to search for a kitchen in the style and colours you think you want on Houzz, there are literally thousands, but you can narrow it down by selecting style, colour, shape, even floors and you might get down to a few hundred.
You can save the favourites on your own profile page or even print pictures off to perhaps compare them and decide that you like this bench with that colour etc...etc...
It's fantastic to see something you like and incorporate some inovative designs into your new build at the same time, so don't forget to search for the newest kitchen gadgets like a slide out knife block or a place for garbage bins or draw organizers, all these things can be viewed on Houzz.
Best of luck.
Cheers,
Barbara

I have designed Island with sinks in the past, great if you are a parent with young children playing in open plan living area, as you can keep an eye on them easier. As I tell my clients do what is right for you as we are all different in likes and needs.

it's great as you can watch TV whilst washing and you're part of the family..not just in the corner doing dishes by yourself..

@jtennr,

It seems you have a few new posts, have you finally decided on what you're doing and have some photo's?

Cheers,

Barbara

Hi everyone - thanks for your input and thoughts!

We have decided to have a small prep sink in the kitchen island, but have the main sink (double bowl) under the window.

Our current house (a rental) has the main sink in the island and there is just not enough room to prep food, stack dishes and have a draining board for clean dishes. So this has been great reinforcement that this has been the right decision for us.

The prep sink will be used for washing vegetables, glasses of water and an ice bucket for entertaining!

No photos as yet - the extension has just commenced but the floor plan has now been locked down.

@jtennr,

Nothing like living with a kitchen that's inadequate in some way or other to help you decide what is the most important thing you want for the new kitchen.

I have so much storage planned for my kitchen and masses of work zones not to mention a doublke sink with double tray, all because I lack so much of these things at present.

A one sided sink, doesn't allow for a hot pot from the stove, and I have just enough work bench at present to roll out a pastry, JUST, so I know I have overcompensated in the new home but I have absolutely no regrets!!!

Look forward to photo's.

Cheers, Barbara

Thanks for your posts @jtennr. I am thinking of doing exactly the same thing. How did your Reno go - are you pleased with your final decision?