Here's what we started with:
The first step from my point of view was to lay out the location for the island. We wanted it relatively close to the counters so the bulk of the traffic goes AROUND the island rather than behind it. But, I definitely wanted room for the dishwasher door to be open and not have to sneak past it. We usually use a quick wash cycle and leave the door open for the dishes to finish drying. So we ended up going with 3.5 feet from the counter on the dishwasher side.
On the end, where the "snack cabinet" opens, we moved the island a bit closer to the cupboards so people sitting at the island wouldn't interfere with access to the fridge. But with the cabinet doors only opening on that end, we could get by with less space to walk.
Once everything was laid out, my brother-in-law attached the cupboards to each other, put on the legs, and added the panels. It turns out that it was a good plan to have his help because there was more modifying involved than we thought. Because we had one cabinet sideways (I wanted the "snack cabinet" to open on the side to keep the kids from coming behind the island all the time), the cabinets didn't line up perfectly. See that arrow? BIL had to plane down one of the panels ever so slightly to get it flush with the other panel.
Once the cover panels were on, our island looked like this:
Standing at the sink, the cabinet on the right will be the slide-out trash and recycling containers.
Here's a side view of the snack cabinet. There will be two stools where our cat is in this picture and another two will go on the side near the fridge.