[svandamme]

if spending 30 k extra for an elevator, when building new.

I'de just get more ground surface and build flat.
Floors don't need maintenance, electricity, nothing can go wrong with them, they always work
And people who are about the retire typically don't need as much room anyway. Kids are out of the house and all that.

If you do need more room, say guest rooms, then put those upstairs and get your own spaces downstairs.