The method I use is quite symple. No modifiers, no new materials, no auxiliary objects.
Just enable wire in Object Properties-->Display. You can do this for any number of objects in your scene with just a couple of clicks. Hide wathever objects you don't want to show in your image , like cameras or lights.
Then select your preferred wiew (camera o 3Dview), display method (for example solid with matcap and AO), press ALT+F10 to switch to full screen , CRTL+F3 to make a screenshot and there you are!
You can show more ore less geometry detail for each object with the subsurface modifier options (number of subdivisions on view mode and/or Optimal Display). Also you can achieve this for the whole scene in the Scene Properties Simplify Panel.
For me it's a pretty quick method. The drawbak is that it doesn't work for cycles rendered images, only for your OpenGL viewport display. So you can't show the wireframe on top of your fancy materials and lighting. Also your screenshot size is limited y your physical display resolution.