Used to do Buenos Aires to Miami (8hrs) to San Fransisco (5 hrs) to Taipei (15 hrs) - with transfers around 48 hrs total - for a few years, all on United. Little sleep, no showers, primitive lounges and huge jet lag. Oh, and Miami immigration was a scramble. "Premium pax can use the Blue lane" boasted the airline, but so did the majority of the other travellers...
Occasionally a Montevideo or Santiago to BA sector got added as well. To be fair the baggage never got lost, and I sat in 1A. All before 9/11. I wouldn't contemplate a US transfer these days, and there are now carriers routing through NZ or Oz.