I would never like my cleanup sink to be on the island, but I can see why people choose to do so given certain room restrictions. I wouldn't want my dirty dishes on display. :)

We also entertain a lot. Actually washing the dishes takes up very little time percentage wise on the kitchen. (I don't do a lot of dish washing when guests are present anyway.) More time is spent prepping and cooking. Could you put a prep sink on the island so you could face your guests while prepping and cooking and then have the cleanup sink on a wall? Do you have a scaled layout you could post so we can offer better suggestions?

Are you doing 2 sinks (a clean-up sink and a prep sink) or just one sink.
If you put the clean-up sink on the side counter do you have room for the DW to be either beside it or around the corner from it onto another wall. Where will dishes be stored for the DW to be unloaded into.
If you do a prep sink in the island are the range and fridge in locations that make sense to do that?
As Breezy asked - can you post a tentative layout?

What Breezy said... But Blfenton follows up well, and we need a layout to see for sure. But a main sink in the island, I think, would be my last choice if a side counter is at all a reasonable option.

i would love to post a layout of the kitchen but not sure how to??

I a messy cleaner upper. This means I splash, spill water
and find I would not appreciate a sink on an island.
I need the backsplash and the deep sink to play about in.
If my kids were doing homework it would be soaked.

I think it depends on what you like and how you clean.
~boxperpups

To post your layout: If you have a scanner or digital camera, you download (upload?) the image from your computer to a photo sharing site, like Photobucket.com, then you can post the HTML (created and noted on the photo sharing site) right in your post or provide a link by cutting and pasting the URL (web address) in the space below your post.

Sorry if I explained in too much of an elementary way...but I tried to explain the way I'd need!

You can also follow the instructions on the thread "new to kitchens? Posting pics" usually located on the first page. The thread has lots of good information for new members so it would be good for you to read even if Rhome's excellent directions are enough.

I always draw my plans on graph paper for posting, but you may have some blueprints or the like to post instead.