I've done it, but prefer to fly, but you might try a freighter, there are a few that carry passengers between the United States and Argentina (BA or Bahia Blanca). I've done that, too!
Sail on a private yacht or on a freighter? I know someone who sailed his own boat to New York and used to know someone whose husband worked on a freighter that included a luxurious passenger section. Not sure if that ship still exists. Anyone have any idea?