Thanks, everybody, for the great feedback and suggestions!

WRT booking on the UAL website, there have been a few occasions booking domestically when I booked a flight online with the "show available upgrades" option chosen, then found after the flight was purchased that the system (and the res agents) would not confirm an upgrade. Is it different with international flights? Or should I just call res and try to make my Visa 5K EQM on other flights?