I cannot really see any functional flaws here (I am sure others will point out what they think). Here are my comments:

1. Good that the counter seating sort of faces towards the living area, instead of dining. That way dining will get distributed better.
2. Prep sink: I was thinking that you could move the prep sink to far right side of that portion of your island. That way, while cooking someone can use that part of the island (where sink currently is), for quick prep work etc. and people sitting at the bar can use the prep sink as bar sink as well.
3. The idea of making the island wider and counter wider is great; it would definitely help cooktop seem more "distant"; which is important since it is a cooktop.

I wonder if the oven(s) is under the counter or an oven stack. If stacked, there is only a 3' corner behind the prep sink on the island for landing space... and that's 4' away.

Are you considering a beverage frig at the end of the kitchen by the D/R and living area?

I love your large island with the informal seating. The shape too... lucky you!!

Might function better to lose that little penninsula with the prep sink. Perhaps tweak the angle and just have a straight line from cooktop through prep sink, with deeper counter.

Agree space beyond cooktop shielding the squatters is a good thing (think spatter, also a handy spot for ingredients, oils, etc).

You have some great features and a nice amount of space. I would prefer to see the fridge more accessible from the living and dining areas. That's the one thing that's most likely to cause traffic through your cooking areas. I'm not a fan of island cooktops, but there are good reasons to have them there in some situations. Would need to know more about yours to see if this is a good choice. I'm generally also not a fan of islands with shapes like yours, but in a 50s home, it could make a lot of sense.

To critique anything else, we'd need to know more about how you use your kitchen. How many in your family? Kids? Ages? How many cooks? How often do you cook? How often do you entertain? Do you bake often? What other kind of cooking do you do? What kind of style are you going for (keeping with the 50s retro look or trying for a real update?)? I hope your kitchen designer asked you all these questions and more.

I was going to say exactly what celticmoon said...I think the return counter with the prep sink causes more problems than benefits, and would cut it back so the run is straight...Although it does provide a landing area. I totally agree that you need the space between the cooktop and the bar so that sitters aren't getting spattered or steamed. I also agree with you that the bar should be 18" deep.

To get a landing area by fridge and oven, maybe put microwave area with its counter space in between the oven and fridge?

It doesn't look to me like you have 4 ft between the oven/pantry cabs and the island...I think you need at least that width to the aisle.

The only suggestion that I have is to lose the prep sink. Just not enough space for it to be very functional and it takes away from your counterspace and base cab storage.

Wow! Thanks to all that have responded so quickly! Lot's of great ideas to consider and glad to here the compliments.

Some answers to holligater's questions (and others...).

We are currently a family of 4, DD is a college junior and DS is a high school junior, so they will not be living at home much longer. Both DW and I cook and the kids are always helping, that's why we went with more space in the center of the kitchen (current kitchen is very cramped). We have a large extended family and will have many future holidays to host. We also want to start entertaining more now that the kids are taking up less of our time! DW bakes more, I cook more; both want to do more of both!

Style? Hmmm.. Our designer had a hard time giving it a name. Definitely updated and not retro. As she said, not quite contemporary. We like simple and clean lines. We're looking at shaker style cabinets, probably maple with a lighter stain. We like the Thermador Pro-style SS appliances, both functionally and style-wise.

On the fridge/oven wall, the ovens will be a stack of two. The cooktop is on the island because there is no place else for it! The current cooktop is on the wall the separates the kitchen from the living room. That wall will be gone and the kitchen extended 7 or 8 feet into the current living room.

Had not considered a beverage fridge, but that's a great idea and will consider it if there is enough room (that is storage).

All "clearances" are at least 48".

Oh, yeah. We are a tall family DS and I are 6-5, DW is 5-9.