I don't like the design for the Newton house work. I know, it's not my house, but I think it's a bit odd. First, in general, that house is absolutely enormous, yet the plan calls for building out more space. I honestly don't think that's necessary. Second, the kitchen plan calls for tucking the working part of the kitchen way around in the back corner. While it is true that old houses were not built with today's idea that the kitchen is a central part of the living space, since they're going to tear out the old kitchen entirely, I would certainly move it to more of a central location, rather than tucked away. Also, what are they going to do with that huge room right next to the entry foyer?
On the 2nd floor, I wouldn't build out onto the sleeping porch. I'd restore it to an open porch, and look elsewhere on that floor for a place to build a master space. Again, the house is gigantic, and doesn't need add'l square feet.

So here's what I'd do: use that existing front parlor as the home office/library. Tear out the existing library (the one they're going to turn into a mud room) and make that the kitchen, so that it would be open two ways: to the family room in front, and to a more informal eating/living space in back, which would be gained by ripping out that bathroom/laundry room (which they're already doing). So the kitchen would be at the apex of a right angle, closer to the family room, placing it in a much more central and convenient location.
Upstairs, which no longer needs an office in my plan because it's downstairs now, the big room with the fireplace would be the master br, and I'd tear out and enlarge the existing small bath next to it to make a new master bath. And then build some closets somewhere
That would still leave three other bedrooms on that floor, which could share the other bathroom. And I'd restore the sleeping porch to its original state. What a great guest room it would be to have a sleeping porch right outside!
The 3rd floor would be the boys' floor. They're old enough, I think, or soon will be (in the meantime they could use some of the 3 other brs on the 2nd floor).

So there you have it, my unsolicited revisions of the project. I was just amazed that with all that existing space they are going to build out more. Not a lot, I know, but it just seems wasteful. The other confusing part is that they said it was too expensive to build a new addition to their old house. But buying this monster and re-doing it inside and out costs less?? I doubt it!

Anyway, it's a really beautiful old house and I'm looking forward to seeing the project proceed!