UA ORD-SGN help needed to Max Miles

I'm trying to get a flight I can upgrade for a speaking engagement in Saigon,Vietnam April 26.

Can't find a full economy fare to upgrade, looking at United and ExpertFlyer.

Do I have to book each leg separately? Direct with StarAlliance partners, not UA?

This is the start of a ton of international travel and I'm just getting into the game, trying to get 1k by year-end.

Thanks!

What are the fare routings?

(1) How are you looking to upgrade? Miles + cash? An upgrade instrument?

(2) Assuming the answer to (1) is miles + cash, you don't need to purchase a fully economy ticket (i.e., "Y" fare) to upgrade. It's possible from any fare, though the lower the fare, the more miles and money it takes.

(3) The easiest way is to purchase a ticket ORD-SGN entirely on UA planes. That means no codeshares. This allows you to (potentially) upgrade all the flights. If you fly a mixed metal itin, for example, UA and NH, you'd have to arrange for the upgrades separately. If you want to go the route of upgrading flights on carriers other than UA, start your reading here, but you'll note this requires purchasing much more expensive fares.

(4) None of the above guarantees anything unless there is upgrade space at time of booking. That means you'll be waitlisted, and that means you might not get the upgrade at all.

Hope this helps...