I'd just have Nightsearcher Trio on each (three) floor that does come on in the event of a power outage. A small adjustment upon activation and they will stay on for 14 hours at half power. I agree that there is not much use in lighting rooms that people arn't in so I light up each hallway with said lights to walk around house ...<snip>....
I have been meaning to order a five pack of these USB lights ever since buds224 posted about them.
I actually bought that whole setup and it works great!
<big snip>
Max
I am such a proponent of "auto on" Emergency lighting, that I wanted to bring attention to buds224's solution/suggestion, for the late comers to the thread who may not have read the thread all the way through. If you don't have auto on emergency lights, when a power failure hits, you might be instantly, in cave like darkness. Just a few units giving off just five or ten lumens each strategically placed can make your home safe so that you can get to your lighting supplies without tripping, or the kids panicking.