I've got a few to speak about...

CO onepass used to have a reward CS7 traveling on partner COPA from caribbean or central america not connecting in USA (Panama City was fine) flying to South America (Buenos Aires, Sao Paulo and Santiago included, and open jaw was OK and free stopover in Panama)...all for 20,000 miles on coach....recently it was raised to 30,000, which is still a great deal, anyways.

I could fly from San Juan, Puerto Rico rntp and use this CS7 award...

Also, on Delta Skymiles... once I flew for 70,000 miles coach reward... using Delta (domestic) and Korean Air (int'l)... went from San Juan to Tokyo Narita via LAX,(NRT 1st int'l stopover allowed outbound), then on to Mumbai, India (final destination) via Seoul, then stopped in Seoul (SEL was 2nd stopover in'tl allowed en route on the return), and then stopover in San Francisco (one stopover enroute allowed domestically), and then finally back to San Juan on Delta... and I got bumped on my last leg and ended up with a $600 voucher! This was in 2000.

In 1997...for 30,000 Skymiles... went from San Juan, PR to Anchorage, Alaska, then stopover in Los Angeles, and then back to San Juan.

Another time, CO onepass was running a 50% miles off reward off a few cities... one of them was Aguadilla, Puerto Rico... I went from Aguadilla to Los Angeles, with a Newark stopover... for 17,500 miles...

Also, on former TWA... I went from San Francisco, stopped in New York, then flew to Stockholm (open jaw), then flew back from Athens via JFK and stopped in Chicago, and finally back to San Francisco, all for 35,000 miles (this is 1992).

On Aadvantage.... went from SJU to HNL... then flew back from Maui and stopped over in Dallas, and back to San Juan...for 35,000 miles...

Also, went from San Juan to Dallas, stopped there, then went to Santiago, Chile, then back to Dallas, and stopped again, and finally back to San Juan, for 40,000 miles.
(San Juan-Dallas normally is 30,000 miles, so for 10,000 extra miles I went to So America)

The key is to book them in advance.

Now, it is not worthwhile for me... I would rather accummulate double miles on paid tickets!