Well first off Canada doesn't have any star'd generals or admirals. We have flag officers. In addition there is only one 4 flag officer and that is the Chief of Defence - he flies via private military plane.

Any flag officer has the option to fly in C (rare to have F flights out of Canada) to his destination, but depending on the situation, some do not do it. If they are flying to Europe for meetings etc., and flying commercial they usually go C. When flying within Canada many of them will fly in Coach. A friend is a Brig. General and he always flew in Y domestically, unless he upgraded with his status. Many will also fly with their troops, if they are a field command officer and flying with those under their command - what is good for the rank and file, is good for the leader.