Thank you all for the advice. This is my first time taking a morning flight at San Diego and did not expect such a long wait at security. There were only two X-ray lines open when I started lining up but they opened three more. Going through security just now took five minutes.

I did check-in the day before and filled out my API online. However, I arrived at the gate after it closed but before the departure time. The plane was not pushed back for another 15 minutes so maybe I could have tried pleading more to be let on. Do jetways ever reopen after they are closed? The most depressing part is seeing the gate closed but the plane sitting there...

I did not see anybody at the priority check-in line before me, so did not get the chance to beg for an upgrade. How much is one upgrade credit typically worth?

I was hoping that Air Canada would have a similar flat-tire rule as most US airlines to rebook late passengers without charge. Guess I learned a $150 lesson today.