Originally Posted by rmlanman

I am assuming you are talking about Complimentary Premier Upgrades (CPUs) on long haul flights to Europe or Asia. International trips are not eligible for CPUs at all. This is purely a domestic benefit (with potentially some exceptions on Copa?).

Alternatively, you can upgrade with miles + copay on most International Economy fares, but your Silver status has no bearing on the likelihood that this upgrade will clear. That depends purely on whether R fare space is available.

As other posters have mentioned, the Economy+ benefit should be available the majority of the time (Intl & Domestic), with the exception of some regional flights that don't have a ton of E+ to begin with.