This Tutorial will show you how to set up render layers correctly using Vray Object Properties. It is a very convenient method of overriding several meshes at once using VOP (Vray Object Properties).
You can override Primary Visibility, Visible in Ref/Reflections and much more.
Check out the Tutorial to see an easy way for easy layering in Maya.
If you are interested in the Scene Files, visit my Dropbox. dropbox.com/sh/b794iu1pkxcv9r9/3YeZSeNCgD
If you dont have Dropbox, register here for free: db.tt/IHNEOgCx