You might consider the airpasses offered by oneworld. I believed the flights are M class.

"oneworld Visit North America: Offers flights serving 200 destinations in 24 countries across the continent and throughout the islands of the Caribbean. Flights are mainly on American Airlines with some by Cathay Pacific and Iberia. Prices for each sector range from US$70 to US$220. Sample itinerary: New York-Boston (US$70); Boston-Toronto (US$100); Toronto-Miami (US$160); Miami-San Francisco (US$220); San Francisco-New York (US$220), giving a total of US$770 for these five flights.

oneworld Visit South America: Offers flights serving 28 destinations in ten countries, with most services by LanChile but some on American Airlines, with fares for each sector ranging from US$80 to US$270 depending on sector length. Sample itinerary: Santiago-Calama (US$140); Calama-Antofagasta (US$80); Antofagasta-Santiago (US$140); Santiago-Montevideo (US$140); Montevideo-Sao Paulo (US$170); Sao Paulo-Santiago (US$235). This gives a total of US$905 for this six sector journey, a saving of 30 per cent (US$397) against a regular best buy fare of US$1,302."

I'm sure Star Alliance offers a similar product with South American covered by Varig.