I think a comfortable distance between the island and the counter is around 42". It seems that you have only 30" between your cook top and the counter. I might be a little too tight. The wall between the entrance and the kitchen could be 4' long instead of 6', you would then be able to move the island a foot which would give you more room between the cook top and the island. Could you switch the location of the toilet and vanity in your dad's bathroom so your enter facing a vanity instead of a toilet which is a lot nicer.

I think the marble naysayers have jumped on the bandwagon without really living with the stone. I have statuary in my bathrooms and love it. Most stains can be removed with a simple baking soda and water poultice. Acid etching is harder to deal with since it removes the polished surface, but its part of having a living stone in your home. If it becomes too bad, you can have it repolished. With a darker stone, you won't have as many issues as a white marble. In order to really know if you can live with it, I suggest you get a small sample of the stone and do some tests. Here is an example. http://www.dohiy.com/2013/04/21/marble-countertops-the-post-acid-test/ Please note that she used bleach and oxyclean to clean the stone after her test. Stay away from both since they can etch the stone just as much as an acidic food. Instead, clean with a ph neutral cleaner like isopropyl alcohol (rubbing alcohol), and for heavy stains, the baking soda poultice mentioned above. You have to remember that marble has been used for centuries as flooring, table tops, countertops, etc. throughout the world and most of these installations are still here and aren't stained and etched to the point that it has been ripped out and replaced. Just think about all of he luxury hotels in Europe and how many times they have been exposed to Hangover type guests without any damage.

You should be able to get everything that you want ........ Are you going to have a cabinet maker build it for you ? I suggest that you work with them and have them draw it up for you........Most cabinet makers are very good at working with their clients to get them what they want.

Usually when you get side panels you automatically have space on the sides. If you have a full depth cabinet on the top, you automatically have space at the top and in most cases you will have leave at least 1 inch of extra room for the back of the refrigerator, so there is always air circulation since everything is enclosed. In the 70's they use to make a small recessed space behind like Fred said, today you don't have to do that, most Ref have flat backs, recessed wiring, not to mention the supply for ice-maker also comes in a flush mounting kits for the wall... so pretty much everything is recessed and only space you need is for air circulation and 1" is more then enough. In addition, if you make recessed area now and you push ref to far you will never get your doors open so doing all that is a waste of time, in addition most manufacturers starting to make 30" side panels.