Last year my auntie had a flight from HKG to Toronto on Y, and the flight was overbooked. The check in agent offers an alternative routing, fly CX flight to Vancover and change to Air Canada flight from YVR to Toronto, and the return flight from Toronto to HK can be upgraded to J. The overall impact is she will arrive Toronto 3 hours later than the direct flight, but got an upgrade to J on the return flight, quite a good deal.

She had another flight to London on VS, and the flight was overbooked as well, and VS offered her to fly on the next day, in return she will get a free ticket to any VS destination which she can use anytime in the next 12 months.....even more generous...

But i never have a luck for such an offer.....