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 need a different type of wm or dw for mounting on top of each other. You cannot do that with a regular machine. Both of the machines produce a lot of vibration. Please enquire with the manufacturer before deciding to do that. My opinion is not to have a wash basin in the dining room. Can you do something like a powder room near the dining area?

Hi,  Go for Jet black granite for counter top. It would look classy with your white ceramic wash basin and beige wall tiles. And go for above counter wash basin.