Mansions - Exteriors with Interior Options
My idea for this product is that the base structure (for use in exterior scenes) could be comprised of 2D planes - similar to how the walls in the M.I.C.K (Medieval Interior Construction Kit) are. They would have regular windows, with the option to add curtains or a faux room cube behind it (to make it look like there was an actual room of furniture on the inside). And actually room blocks that could be added in for rendering interior scenes.
This way, you could load only what you needed, thus saving resources. The grounds surrounding the houses would have pools, hot tubs, tennis courts, guest houses, 4 car garages and boat docks. Think Beverly Hills and Palm Beach type mansions. Or even Michael's house from GTA5!