@Dan you really wouldn't recommend the AC Thursday flight? What's the worst that could happen? If the flight is delayed >2 hours, you don't board. If it's less than that, even if you're stuck on the runway for three hours, you make it no problem.
Plus AC is not an operational mess like LY
Not in the winter.
My calculus has changed after being stuck on the plane to my Zayde's 90th.
Even after allowing for a 2 hour delay and 3.5 hours on the runway like El Al, you can still be forced to fly.
The margin of error has to be 8+ hours I think, unless there are extenuating circumstances.