Why are CiviCRM fields not displaying from a view in a panel in Drupal?
It turns out the issue was not specific to CiviCRM fields.  The issue is in the relationship between Views and Panels, specifically, passing arguments between the two.

The missing piece for us was using the 'Argument input' setting in Views to pass the arguments properly.

Eventually discovered a great post about it here:
http://www.metaltoad.com/blog/passing-page-arguments-view-panes

I won't try to reproduce it.  Following these steps solved our problem.

Enjoy,
Lewis