This is very impressive!
I’m working on a interieur visualisation at the moment and I have to try the 6 directional lights. 
Do you have the “Lower Hemisphere is Black” Checked in the Skylight?
May I ask how many people were working on this project and how long did it take to get to this stage. Also How many of the assets were already done and how many did you need to make yourself? Just a rough estimate would be nice.