@Dan: that's just how the challenge goes, and I forgot to mention that he cannot go twice to the same airport.
The trick here is to pass as many airports as possible. But preferably moving the least possible eastwards, since you cannot go westwards. Add to it, as a bonus that if the latest flight in the day can be a red eye, he does not need to waste time + money going to a hotel.
So a yvr-yyz would be the worst flight you could take.
I'm not so familiar with usa airports, I thought that some rooky here would have some ideas.
Even if finding something in the middle of the journey, we can puzzle it together later.
It would be very embarrassing if I were to find the best options...