I've done about a dozen AONE'4s over the last 10 years, and still feel you can gain a lot of value over and above a DONE4. An example of a "barebones" itinerary I use is:
BNE-SYD-LHR-JFK-LAX-HKG-SIN-SYD-BNE
That gets you a very good sample of Oneworld F experience:
- SYD-LHR in QF F, inc SYD F lounge
- LHR-JFK in BA F (albeit not BA A380 I don't think at the moment), including time in Concorde Room at LHR. AA F is an option, but won't get Concorde Room access as departs T3.
- JFK-LAX in AA transcontinental F, inc Flagship dining at JFK
- LAX-HKG in CX F, inc LAX F lounge
- SIN-SYD back in QF F (or BA F)
If you want to include BA A380 experience (working on memory of A380 routes), you could do LHR-LAX, make your way back to JFK, then do JFK-HKG in CX. The AA transcontinental F is the least impressive experience, but still nice enough to sample.