It would be awesome to set up a day or night feature for the user/viewer. So for example I am working on a scene now that I would like to show with the option of both at night and during the day. - As both options have their own charm.
So if a slider could be introduced that as the user slides from day or night it would become dark or light and also emission shaders and lights could come on or off, and work in parallel with the slider.
Or just have the option of a tick box to change from day tonight.