i'm happy to help. i'm not motivated to do a proper scene myself (i think i would get bored or frustrated with all the animations and scripting), so i tend to play around witht what others have created.
be careful with the images i posted, they are indeed your scene without significant changes and only use 3 lights maximum (mostly two light only, as the effect light is only used on the mirror scene (light bounce fromt he mirror) and the standing outside kamasutra scene (light from streetlevel shining upwards to give somedefinition on her face and interesting shadows on the bodies) BUT i had the day/night cycle stopped and for every picture deliberately aimed the sun / moon light for best effect and also moved the ceiling light around a bit for optimal effect. you don't have that luxury, because you decided to go the ambitious route with the day/night cycle
on that occasion i realized how difficult it is to get that cinematic lighting with a day/night cycle (but i still like the idea of it - it just complicates things a lot
)
some ideas on how you could cheat a little bit:
-> cheat light (described already - as a last resort. it's also a nightmare to properly tune, because it would have to change per scene and depending on time of day). if you increase the shadows on the directional lights, you'll need this for every day scene to simulate light bouncing back from the wall in the back (in my pictures i did not do that, because the ceiling light was enough to brighten the shadows, but this is to some extend what i critizised with you room light (a practical light being missused as an effect light. in this case the effect was exactly the same, but you could argue that it would have been cleaner from a workflow perspective to switch of the ceiling light at sunrise and bring in the effect light to simulate the light bounce)
-> cheat with the moon light: since you don't have the direction animated, you could maybe aim it differently for every scene. of curse not realistic, but it might make things much easier. with this you could easily get the look from my pictures - in the night scenes at least - because you could aim the moon light per scene and contrast it with the ceiling light without needing a third light (i only used third light for outside kamasutra and mirror scene).
another important thing is global illumination. i don't have any definitive advise here, as this is something that works quite different in reality and even works differently in every graphics engine. i'll just tell you what i did, as a suggestion to try out, but i think this is not only a question of style and aesthetics, but mainly a question of workflow, especially if you do day/night.
in short, i did not want to bother too much with GI, because it is a headache when you cannot dynamically change the skybox in a dynamic scene imho.
i however needed some GI very badly, because i increased (maxed) the shadow strength on the directional light, which does not work on the cityscape without GI (compeltely black shadows on the cityscape) , so i set GI to default values and from there decreased it as much as i could, only looking at the cityscape with sun coming from behind the buildings (on the scene itself you can always light up shadows with your practical light, or cheat light, but you don't want to bother with that on the cityscape environment)
you could argue that it would be realistic to decrease the GI dynamically at night, which is true, but i found that it did not make that big of a difference, so i did not fiddle with it any further.
i did however use the camera exposure slider a lot and this might be a good idea to animate with the day/night cycle. i tried to somewhat mimic a pbr (physical baased rendering) workflow, which means that the sun is significantly brighter than the moon (i think i used only double or triple values, so not really physically correct) and then at night i increased camera exposure to get the brightness where i needed it. why would you do this?
only reason here would be that the ceiling lights would have somewhat realistic brightness compared to outside light. they have always the same brightness value, but as the sun goes down they appear brighter, because the exposure gets up (hooray for realism!).
if you only do light for a single picture it does not matter if you change brightness values on lights or camera exposure, but when you have a dynamic scene, it's cleaner to keep brightness levels of natural light (sun/moon) and practicals (ceiling light etc) in a somewhat realistic relation and control brightness with the camera exposure slider.
can't think of any more. hope that helps.