I can't imagine that this could have "just" worked (simply trilaterating using signal strength). If the laptops & kindle were in outer space, I'd believe it, bu

I can't imagine that this could have "just" worked (simply trilaterating using signal strength). If the laptops & kindle were in outer space, I'd believe it, but wifi signals indoor get attenuated by obstructions, curve around things, and bounce off of things. This is one reason wifi localization uses fingerprinting instead of trilateration. I'm guessing OP primarily ended up using the signal strength from one of the laptops, and just did a hot/cold chase through the house.