Sarah,

We have not yet prioritized porting all site amenities to Rhino. If enough Rhino users chime in regarding this, that would help. Our current priority is in porting things to Revit, which is scheduled to take at least a year. Rhino could be scheduled after that.
This is also the first we have heard of a desire to bring over layers and linework. It was a priority for SketchUp due to the lack of UCS support with its DWG importer, and the relative difficulty in bringing over a very simple file (such as the hidden setting for Units). My understanding was that Rhino was not as constrained.
I'll get these noted for the Rhino wishlist.

--J