Thought other GXR users might enjoy a thread like this. The GXR is such a configurable camera, on so many different fronts, that a notion of what works for you might be useful and instructive for others.
A recent favorite setup for me: GXR body, A12 Camera Mount, Color Skopar 28mm f/3.5 and Voigtländer 35mm optical viewfinder. The 35mm OVF presents just about exactly the actual field of view (not calculated, tested) of this lens on the GXR-M sensor and this focal length has enough DoF at f/5.6 to work beautifully using zone focus—set f/5.6 and the focus zone runs just shy of infinity down to about 5.5 feet. I set the "Zoom Display Release" to OFF and turn off the LCD, that way when I need to check critical focus, the display is normally already set to zoom mode by pressing the EVF/LCD button to turn it back on.
Works a treat, and the tiny Skopar 28mm is a very nice performer too!