We'll be retiring soon, and have been thinking about spending a few months in South America. We are not rich by any means but we love to travel and have managed to do quite a bit on a tight budget. Some "musts" on our list would be Machu Pichu, the Galapagos, and Iguazu Falls. We have friends in Rosario, Argentina where we'll spend some time---maybe even go back and forth from their place to "rest up". Would appreciate ideas about best times of year, where to start, other "must sees" etc. from some of you seasoned travelers out there especially those of you who are thrift minded and appreciate "good value for money" as my Brit expat husband would say! We are in our late 50's but fit and relatively adventurous. Thanks for any help.