I like Continental's 20K round trip coach award within Latin America. You cannot trnasit the US, but with COPA, you can travel just about among any major cities in the Caribbean, Central and South America via Panama. Service is good and the connections are well coordinated.

COPA has flights to Panama from Cancun and San Juan, so you can find a cheap charter to Cancun or a cheap flight to SJU and use COPA from there.