There are some stairs near here that I use that have a slope next to them for pushing bikes up. I've discovered that it is best to walk up the slope and down the stairs. For safety, comfort, pleasure, the lot.
Why not have this for the home? If your staircase is too narrow a button could turn the stairs into a slope (and back again of course!). You could also slide down the slope if you fancied. Reckon it would cost about £400 per home.