The challenge in my mind is always getting that international seat released. Domestic awards are generally much easier to released for two reasons. First domestic seats can be released from a larger fare bucket (e.g. D discount business or N discount economy versus I super-discount business and Q super discount economy for international). Second, generally speaking no one cares about flying business domestically. I mean if you are flying say Sydney to Los Angeles and have a 1 hour connecting flight up to Brisbane, are you really gonna care being in economy given business class generally consists of a slightly larger seat? I certainly wouldn't!
Generally, how this works is you'll call up Qantas, you'll tell them where you are flying from and flying to (i.e. final destination) and they'll sort out the rest. Going back to my example, last week, I need to book Sydney to Detroit. So called up Qantas to see if a release could be facilitated. I requested Sydney to Detroit, and had the specific flights I wanted (this obviously was researched before I made the call) with me asking the agent if they could release the Qantas flights that aren't available. As it would turn out they couldn't release the preferred flights I wanted (SYD > DFW or MEL > DFW) but they could get BNE > LAX and SYD > BNE released for me. Yes it does mean I'll need to overnight it in LA, but I would've had to overnight it in Detroit had my desired itinerary went through (it's generally not safe to take buses from Detroit airport to Windsor, Ontario at 10 PM). The agents over the phone can stitch in partner flights if needed. So for instance, if you were flying Sydney to Phoenix, Arizona, and managed to get Qantas to release SYD > LAX for you, the agent could add that connecting flight from San Francisco to Phoenix on AA, provided there is classic award availability on American.
You are correct but there is a wrinkle here. There are several
different distance based award charts used, which one Qantas applies depends on the itinerary chosen. The cheapest would be the JetStar award chart which would apply if all of your flights were with JetStar, JetStar Asia or JetStar Japan. The next cheapest award chart would be for awards that contain strictly flights from American, Qantas, and Fiji Airways. Lastly, the most expensive would be the partner award chart which would be used if your trip has a flight operated by another partner like LATAM, KLM, FinnAir, British Airways, etc. Importantly, the moment your award ticket has a flight operated by any of these partners, the whole thing is priced out using that table. So for instance, suppose you are flying from Sydney to São Paulo, Brazil. You got a Qantas seat released for QF27 from SYD > SCL, and then connected onto the LATAM flight to GRU. The whole itinerary would price out under the partner award table and not the Qantas table, even though Qantas operated most of the trip.
Then there is the whole matter of OneWorld classic awards that allow you to travel the world business class on OneWorld partners for peanuts. But that's a
discussion for an AFF article.