Not too much better, but I routed through CLT instead of MIA and BOS instead of JFK:
SJO-DFW-CLT-DCA-YYZ-CLT-LAX-ORD-BOS-MIA-SJO
It prices out to ~$927 on AA (though Google also says $943) for 11095 miles.
https://www.google.de/flights/?curr=...1800-2400;eo=e