I am seeing some odd fares, especially high on Air Canada so nearly full flights already for May?
For example, PHX-YYZ May 6-11 Base Economy:
Porter $325
Air Canada $940
Both on same page per Google flight and non-stop. Assume this is $CDN doesn't say but looking up from US

Or
Air Canada PHX non-stop $693
Air Canada with a stop in Denver just over 1 hour between flights $161
Again not sure if $US or $CDN but both would be the same currency. Our exchange rate is now about 0.70 CDN/USD

I have lots of FF miles on American
I would up booking American one-way Business class via ORD using 29k of 350k FF miles It leaves PHX at 5AM but can do this.
Return via Porter Business Class US$263 non-stop