Green Designs came up with a great plan, as usual. It's very similar to my new kitchen. The aisle between my 9' island with prep sink and the rangetop wall is about 42" counter to counter. Its perfect. I've had much larger aisles and hated them. In fact, that's one of the reasons I reno'd my old kitchen. I'm the sole cook in my kitchen 99% of the time, and I would never, ever, ever give up my prep sink. Ever. I love having a large prep zone with a dedicated water source that I don't have to share with the cleanup zone. I'm usually the one who does the dishes too, but when DH occasionally does that when I'm cooking, he can do it out of my way. This kitchen is my first experience with separate prep and cleanup sinks, but it has changed my cooking habits and way of looking at things in the kitchen. You will not use the sink on the perimeter to prep the way you laid out the space. It's not convenient for daily prep. It is a great place for a cleanup sink. Being over on the side like that, your dirty dishes won't show much. Mine don't. Between the giant single basin cleanup sink and the perimeter location, the few dirty dishes waiting on the counter for the DW don't both my OCDness very much. And as you can see, my kitchen is open or at least semi-open to all the other rooms in the house and to the front door. I much prefer an island being all one height rather than bi-level. Your first inspiration pic island is one height. At one level, you can spread out for large baking/cooking projects and for school, sewing or crafting projects. A large kitchen doesn't have to have wasted space. It just needs to be laid out correctly so you have the right amount of space in the right zones. I agree with everything Holly said. I think you could have a great kitchen here!

"My concern is that it Would be very annoying to not have enough room to wash your hands without them bumping the back of the sink." Well, it depends on the particular model. Some "regular size" faucets are smaller in scale than a prep sink faucet in a different model. You've probably noticed that, like many things, faucets have generally been "Supersized" in recent years. In any event, most "prep sink size" faucets are only a bit smaller that the "regular" size in the same model. Here's a picture of my prep sink size Ladylux in my main sink, which is 25 inches interior width. I have 6 inches of clearance between the back of the sink and the water flow, so bumping the back of the sink or faucet is not an issue at all. There is also more than sufficient spread even without using the pull down feature. Note that I also tested the "bar sink" size of the same faucet, and that one looked a bit small to me given the overall scale of the sink and kitchen. Sorry for the mid-construction pic, but I thought this showed the prep sink size faucet in context of the scale of the rest of the kitchen. Bottom line: pay close attention to the spec sheets of the faucet you're contemplating, and make sure the clearance from the back won't be an issue.

Whether it will work functionally depends on how far the reach is. A 15" deep sink will be overpowered by a faucet w/a 9" or 10" reach and will block easy access to the sink when the water is running. I need my hands in the sink much more at the Prep Sink than at the Cleanup Sink. So a faucet that sticks too far into the sink would get in the way. My Prep Sink faucet actually is a bit too deep for my 15-3/4" square sink...and it has a 9" reach. I think a 7" or 8" reach would have been better.

We have the water filter at the main sink. Not only is it closer to the glasses; it's closer to the espresso machine and tea things and to the baking center. That's convenient for making bread dough. We also find other advantages to having it at the main sink. Ours is instant hot water as well as cool. When cleaning just a pot or two, it is convenient to add some hot water from it to the tap water to get warm water for washing instead of waiting for the hot tap water to arrive (and it saves water). Someone who needs water doesn't have to disturb someone using the prep sink. For example, getting rice started while someone else preps for a stir fry.