I too am trying to figure out the new upgrade rules on the new domestic fares, Fun, Latitude, Freedom. The AC website (as well as Aeroplan) has NO info on these rules, at least nothing I could find.

I assume FUN is not upgradeable, but what about Latitude.

Why has AC not spelled out the rules clearly on these new fares??? We are all familiar with the H fare rule, but what of these new ones.