Hi Jeff,
Sounds like a cool idea what you're trying to do.
Have you seen the 3DCity workflows? The one on analysis has a workflow to put points onto facades in CityEngine, which can then be used to perform 3D analysis in ArcGIS.
http://www.arcgis.com/home/item.html?id=84a432d1b26d4fbfac3b0feb3359fa12
Not sure how it would work with taking neighbouring buildings into account, perhaps it could work if you made a raster from the 3D building dataset on top of the terrain.
Not sure if this will help, haven't done this myself yet.
Thanks
Nathan