As a general rule, the value of lounges is inversely proportional to the general quality of airport. They can be a godsend in developing countries (sometimes the only air conditioned place in a tropical airport), or very mediocre airports like a lot of the American airports (LGA, looking at you). And they're also nice in very expensive countries - ZRH, OSL, LHR - where coffee and a muffin will easily set you back $15 CAD.

But for the Canadian hubs - YUL, YYZ, YVR - they are increasingly irrelevant.