Eventually when you come to resell, a pool is an added plus. But for your own purposes, emptying the pool and adding a deck over it with a hinged door and steps placed below would be great for storage (as per option b but bearing in mind you could revert). All the best for your lovely new home.

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.

Leave the vanity in the ,space needed in a walkin is personal but in a 8 x 8 if you put storage on 3 sides you will have quite a lot of space, figure out what you have now and see if it will all fit or will you need dressers in the MBR

@Rock Doc: Are you addressing this to me? I haven't actually bought these tiles yet - when I do, I will definitely be going for the handmade ones. They're a work of art and irreplaceable in my opinion. However, there are also screen-printed tiles available in the market in more or less the same patterns; the workmanship is of course different, but you get them cheaper, and they're also more easily available. You could give that a shot. I'd recommend Aakaar Flooring Solutions - they're here on Houzz and are able to provide both the above-mentioned types.