First - thanks "ALW" I had never seen the mapping site you suggested - it is great - living in Regina I am always trying to figure which route to take and which airline to use.
I hope changing the itinerary to CUN is not going to be a big problem - I was hoping that if I offered to pay the hotel they would consent to changing my return to CUN-YYZ-YQR instead of my booked (changed to extend stay and only seats I could get for Classic Reward) CUN-DEN-YYC-YQR. After looking at miles I see it is only 100 miles further however, will have to clear customs in two countries and one more connection(which is always a concern).
I want to say that in the past most of my experience with AP agents has been positive.