It sounds like you made a terrific buy on the cruise. We, too, made our own air on Expedia, going Denver-Miami-Rio-Iguazzu Falls-Buenos Aires. We cruise on the Renaissance R2 Buenos Aires to Valpariso around the Horn, then fly back Santiago-DFW-DEN. We too realized a considerable savings on the air, plus getting miles on AA and probably better service and connections. We will have to arrange for our own ground transfers in Buenos Aires and Santiago, however.
Have a great trip.