Some of this functionality has been available a while, but I've refined it recently so update rhino and revit plugins from http://www.geometrygym.com/downloads
With the release of 2015, Revit has enabled some more generic solid generating functionality.
At the moment it enables plane faceted objects (with straight edges) and extrusions. I've been putting forward requests for further improvements (including masking of internal edges with co-planar faces adjacent) and if more users do so, the faster we'll see this materialize.
Grasshopper is a fantastic tool for projects such as sports stadia, so here's a slightly simplistic example of generating some seating tiers. You can use the IfcFacetedBrep shape representation with a categorization of an IfcSlab object (as a floor). Here's an image of the resulting Revit import. Note that it's not really possible to edit the object downstream (although I am working on improvements for updating the model).
here). Here's the Grasshopper file (Rhino document units should be mm) and here's the resulting IFC file.
So this works for faceted objects with plane faces and straight edges. If your shapes don't meet this criteria, one of the few options remaining for the time being is to import a SAT (or DWG) into a generic model family. My tools can automate this process, allowing automation of categorization and assignment of parameters/properties.
Here's an example file to demonstrate this. Rhino Grasshopper (Grasshopper model with new Revit Components) Note you can right click on the ggBake component and set the .SAT generation of IfcRepresentationMaps. Also make sure you're using IFC4 if nurbs are applicable. An IfcRepresentationMap is similar to a block in Rhino or a family symbol in Revit, ie a master geometry that is defined in the project/model as transformed instances. Here's the resulting IFC file.
If you have suggestions for improvements, please let me know (enabling more categorization is on my todo list). The more that also contact Autodesk asking for more and more functionality to generate geometric objects the more likely we'll see earlier implementations of improvements.