Arlene, definitely consider doing the Amazon -- we've done it twice and would do it again in a heartbeat. My favorite excursion there is the riverboat trip up into the tributaries -- They let you fish off the boat and I actually caught a Piranha on one of our trips. They cook it up and everyone gets a taste. Tastes like chicken :D
I also liked the stop in Alter de Chao (sp??)--a cute village where the children all come out to meet you and take you to their homes to show you their pets (like a sloth or a snake --eek!). Definitely put it on your list.