Thank you all! All the detailed answers have helped me a lot. Now I think for this summer, I just book a single RT. Like somebody says, sometimes "cheap price" actually urges people to spend more, hehe. I am just afraid that I won't be able to complete all the 6 flights within a year.

To Beepyou:

Yes, I don't know why that person comes out with a different interpretation about the expiry date. Anyways, it is very clear now. Thank you!

To Zorn:

Thank you so much for all the details! It seems AC is playing trick on lower fare ticket. Well, it seems no way to have a better deal on a single RT. If you have a better idea, please tell me.

So I can't have "stop-over" with the flight pass, pity.... but YVR-HKZ flight pass can work too. I will think about it next time.

I purchased two RTs last year and AC gave me some top-tire upgrade to executive class, which I can use for this travel hopefully. So far I think the Aeroplan is working well for me.

Haha, Queen's sucks on something because it is a smaller school compared with UT, McGill, UBC. Well, I want to attend a small school for undergraduate and now I think I have made the right choice going to Queen's. I enjoy studying here honestly, but for other things, especially leisure - just forget it

I am doing Arts as well, double major in Economics and Music. This unusual combination probably can be found only at Queen's. I was accepted to McGill back then but after I received Queen's offer, I rejected all other schools, hehe. Now I have a prof in music is actually from McGill (he is adjunt-prof for McGill and Queen's). I know McGill has good music school, so I am feeling lucky, hehe.

To BlondeBomber:

Thank you for your tips! It's so true there are many trade-off for this cheaper flight pass.

Hehe, low-season, I can't really tell when exactly it is either. Hope someday flight is just convinient like train.

By the way, I assume you have used some upgrade certificate. I just received two top-tier executive upgrade for international flight. Will it be difficult to have the upgrade during July (high season) because of limited seats? This summer is the only chance I can use them.