What are the dimensions of the top, and will you have an overhang for seating? I think deciding that might help...

The dimensions for the first picture is 36" w x 66" l. The overhang for seating on each side would be 8" under the narrow end of the island. The dimensions for the second picture would be something close to 34" w x 66" l. The second picture is the one that is giving me a problem, because I am not sure how to arrange a countertop for this shape and space. The space is narrower on the left side. I don't know what to do.

When we recently rebuilt our island, we decided to put it on wheels...it's all about the options. Now we can move it if we're having a big dinner party and want to open things up more. The wheels lock in place, so there is no movement once it's in place. The only drawback to this design is that you can't hook it up to electricity, therefore no outlets in the island...or sink, or oven etc. We use our island as a bar/eating area, with lots of drawers on one side. I love that it can be moved.

In both pictures, the island looks too close to the wall on the left, but it's hard to tell from this perspective if this is the case. Do you have a floor plan with dimensions we can see to get a better idea of distances?

NKBA layout guidelines specify that a counter height island should allow for a 15" overhang for seating. Are you intending to have the countertop overhang that largest cabinet by another 15"? If not, is the difference in width between that shallow cabinet and the wider cabinet 15" that you could then use for leg room for seating? Either way I like the second cabinet layout better for the island. If you will have an extra 15" overhang, I'd suggest using that empty space (with the second layout) to build some more storage. You could have a long narrow cabinet for cookie sheet storage. Or shallow depth shelves for cook book storage. Regardless I would try to find some usage for that extra space.

NKBA layout guidelines specify that work aisles should be no less than 42" for a single cook or 48" for multiple cooks. How much space do you have around the island to the surrounding cabinets?

Without dimensions of the space, it's difficult to give you more than general advice...and PricklyPearCactus hit the high points:

Aisle widths...Do you have adequate aisle widths on all sides? Be sure you're measuring aisle widths counter edge-to-counter edge, not cabinet-to-cabinet! Counters usually stick out approx 1.5" from the cabinets. So if you're measuring cabinet-to-cabinet, your actual aisle widths will be 3 inches less than you think they are now.

Unless this is always a one-person kitchen (never more than one person in the kitchen at a time), I would strive for at least 42" of aisle width b/w the island and wall runs. You could probably get away with 36" on the short end (where the range is going to be, I think), but I would strive for 42" where the sink is. You not only have workspace to consider, but also an open DW.

The aisle width behind the seating needs to be at least 32" if there's no traffic or cabinet/counter/appliance behind the seats. If there's appliance/counter/cabinet, you really need closer to 60" for room for both seating and working on that aisle. If there's major traffic, you need at least 48"; minor traffic (less used thoroughfare) and you can probably have only 42".

Seating overhang should be 15"...Skimping on the overhang to make seating "fit" in a space will not work, especially if you have a cabinets/counter or traffic behind the seating. People will take up the same amount of space whether or not you provide adequate overhang...the human body can be squeezed in only so much! What will happen with inadequate overhang is (1) people will have to lean over or sit sideways to reach the counter and (2) the main part of their bodies will be farther away from the edge of the counter...meaning bodies will still take up the same amount of space as if you had provided the proper overhang...just more of their bodies will be in the aisle itself...blocking traffic or getting in the way of any appliances or workspace behind the seats.

So, what are the actual dimensions of the space? Or, at least the actual aisle widths, how they're measured (counter or cabinet), and what's surrounding the island? We cannot see what's on the left or most of the right.

We would be doing you a disservice if we just assured you "everything will be fine" without more information!

I'm going to be honest here and it may not be what you want to hear, but....

Do you really need seating in the kitchen? I suspect that's what's causing the problems here...

What about having just one seat on the very end? You could get (or build) shallow cabinets or shelving to fill in behind the run of cabinets...

I understand you want seating, but it may not work out... I wanted an island w/seating in my kitchen, but I finally had to accept the truth that it just wasn't feasible...I ended up w/2 seats at a peninsula w/seats outside the kitchen-proper, but not on an island.