I also, have had flights cancelled once upon a time - one was a SAN-PHX. When I got word at the gate, instead of waiting in line behind most of the pax that had started to form a LONG line up to the GA, I just exited security and went back out to the ticket counter. They wrote some rule on my boarding pass and told me to go to WN for the flight... my original HP flight was at 5pm and the WN flight I got on was at 5:05 (or something like that). Other than the SSSS I got from WN (probably for the last minute & one way ticket.. haha), I got there just in time to make my YYC connector - and was quite pleased with how HP put me on WN immediately.

Another time, my YYC-PHX flight was cancelled one morning (HP 246 at 7am) and my final destination was SAN, arriving at 11:40. HP called me 6 hours in advance on my cell, and had already rebooked me on a UA flight leaving at the same time getting into SAN at around 11:45. Aside from losing an HP F seat (UA instead, was great enough to put me in E+ since I was *S from AC Prestige way back when...), I was, again pleased at how they handled my cancellations - it was almost seamless.

I'm sure, both times the fact that I was waving my Platinum card helped the situation a bit.