As mentioned, getting bumped up to a higher service class on a long haul, international flight is a LOT different than getting bumped up in domestic US (even if it’s a really long flight).
I fly a lot, and have flown quite a bit overseas. I’ve been bumped up to business from economy twice (that I recall). Once was fairly unexpected, on a flight from Amsterdam to the US, and I assume it was because coach was oversold. On another flight, I took a bump the day before, and brought fresh made chocolate chip cookies to the service personnel who were pretty nice about it when I came back the next day (I got bumped at my home airport). Some combination of the two (bump and cookies) got me up to business class on Delta, which at least at the time had eliminated first class on US-Europe flights.
I did luck into a “under the table” bump from business to first on a flight to Europe. I got on the plane and found an older man already in my seat. He had a first class ticket but preferred to stay back in business with his wife, so he offered me to just take his seat. I checked with the flight attendants and they didn’t have a problem with it. Nice to have a lay flat sleeper for that flight.
On United you can combine miles and money to upgrade your seat. I was going to do this on a flight to Singapore, forget how many miles but extra dosh was $500 when my company made me switch to another flight/airline.
As a FF with United I can use miles or systemwide upgrade that they give me to upgrade on an international flight. You might be able to BUY these on Amazon (or from me, send me a note
) but there is a chance that even with these you won’t get an upgrade.
Even though it may seem random, most upgrades are part of a process. Continental’s domestic process is to offer to sell upgrades, then offer them to their Platinum members, then to whichever of their FFs has paid the most for their seat. For United they do it based on Global Services members, then 1K, then Premium Exec, then Premium. They break ties based on who was on the list first and who has the most lifetime miles. I’m sure that other carriers are similar.
I’d rate the chance of a random couple getting an upgrade as being extremely low, especially if the airline has people who spend a lot of money with them every year that they could take care of first. Doesn’t mean it can’t happen, but…