The OP mentioned this being their last house.
One can never really know their health as they age, but if you plan on living in the house until it becomes impractical, I would plan for it in your build. e.g. Never know when stairs will become issue due to joint replacement. General mobility issues. It didn't happen to my dad until his late 80's, but in a 4 year period he went from being able to walk 9 holes to needing a walker.
Also if you hope this is your "forever home", I would focus on downsizing and keeping things simple.
Depending on your current age, some of the things can be added later:
- Since home will be multiple stories might want to stack 1st & 2nd floor closets for possible shaft for future people lift .
- Walk in shower with bench
- Higher Toilets
- Toilet location to allow for wall rail.
- Wide doors and walk areas to allow for walker/wheel chair.
Lighting is an area I updated in my home.
- Motion light outlet for overhead garage light. Great if hands are full leaving/returning home. Also work well in stairwells.
- Also like night lights. Hate having bright lights making me wide awake when taking a leak in middle of night. They make wall outlets that have LED night lights built in. Also great in stairwells