I wish I could give you general recommendations but as anyone who has read my posts over the past 7 or so years knows, I design custom homes and renovations using a process that does not begin with finding a plan. I only see pre-designed houses when they are posted here. For example: One of my clients hated stairs and by the end of the design process the entire house was square with a series of quadrants spiraling up around a central stair. It had turned out that it was floor levels that did not communicate with each other that she hated. The top level overlooked the living room and the view of the Green Mountains was spectacular. It was actually pretty inexpensive too. Another client had an extensive art collection so I put a wide formal hall along one side of all of the living spaces. I recently visited it and the second owner had a far better collection; It was like a grand gallery in a museum. A client on the Cape had bought a 60's Yankee Barn with a heavy timber exposed structure and a 2 story living room. In the winter they were so miserable in it that they hired a local architect to build an addition next to it so they could use that in the winter and the Barn in the summer. No matter what they did they couldn't get satisfactory lighting in the living room. I took over the job and finally convinced them to say goodbye to the Yankee Barn and put a second floor in the 2 story space. They saved a small fortune and we saved a few beams in a bedroom as evidence of it's history. IMO the design of a house is a collaboration between a family and a designer. I believe I am able to create good solutions for people because I listen to them very carefully and I am not afraid to suggest unusual solutions. Of course, I always let them feel that they were part of that discovery because, in fact, they were. So all I can recommend is to start at the beginning of a structured process and allow everyone to be part of the process by carefully moderating the discussion. CAD floor plans can be so restricting and distracting during this process that I try to only show clients a hand drawn sketches until it is time for final design approval. A CAD drawing acts like Vonnegut's Ice Nine. Here is the dreadful Yankee Barn:

I have no knowledge about building of spiral staircases, but I do know something about their history, and that might interest you. Mike mentioned that being right-handed makes a difference in the "feel" of walking up a spiral staircase -- he's on the right track. Back in the middle ages, castle owners designed spiral staircases to benefit a right-handed swordsman. The stairs'd be built so that a swordsman could stand on the wider portion of the step and have full use of his right arm. In contrast, his opponent would be forced to fight while standing on the narrow end of the step, and use of his right arm would be impeded by the staircase itself. His chances of winning his way up the steps was greatly impeded by the design. Wanna know about murder holes? Arrow loops? Crenelated battlements? Parapets? One of my degrees is in history. In more practical terms, do you have any experience with spiral staircases? I thought they were super cool until I stayed in a beach house in which the second floor was ONLY accessed by a single spiral stair. Getting a suitcase up those stairs was a pain. I wouldn't want to move a bed upstairs or carry laundry on a regular basis. I think a spiral staircase is cool as a second staircase ... but not as an only staircase.

I’m not an absolutist curmudgeon against all remodeling. Do No Harm isn’t applicable to the 00’s McMansion. Or some of the 70’s tract ranches. All of the harm inflicted on those was done in the beginning, and they have no place to go but up. But you just know that some Philistine somewhere sees Falling Water as just some pile of leaky concrete and stone and would propose bulldozing it in favor of a Mini Mart and 24 hour bait shop. Not every home needs to be preserved. Just the well designed ones. This is a well designed home. So much so that any changes should be approached only by ensuring that they are in harmony with the original intent of the design. It’s physically painful to think of anyone putting up shiplap and painting any of it gray. 10 minutes fads are usually bad ones. Wait 5 years If its good design, it will still be good design. If it’s bad design, you’ll wonder what you were thinking.

Yes, if never used spiral stairs before, you have to pay attention. When I was in Amsterdam we had them in the hotel, (it seems there is a lack of fire regulations there as egress goes). and elevator you can barely fit 2 people so I used stairs all the time, they are fun and add nice detail in some circumstances especially when you tight on space, or if there is a loft, to down into the basement as the second stair, etc... but if you have small kids in the house, they can be dangerous if they're not careful.