You can use 3D design software (such as Autodesk 3ds Max®, Google™ SketchUp®, or Form/Z® by AutoDesSys, Inc.) to create large-scale massing studies, and then use Vasari to associate host elements (walls, roofs, and so on) to the mass faces.
In order for Vasari to understand the exported geometry as a mass object, use the design software to create a design, export the design to a supported file format (such as DWG or SAT), and import the file into a mass family in Vasari. Vasari then treats the geometry as a mass, allowing the faces of the mass component to be selected and associated to Revit host elements (such as walls, floors, and roofs).