Peggy and Claudia,
Thank you so much for all this good advice. We're in the process now of figuring out just what we're doing! So far we have:
Amazon River Cruise (see huts and river people)

Samba Show in Rio

Tango Show in Buenos Aires

Iguazu Falls from Callao, Peru (we didn't like RSSC's 11-12 hour all day tour so we booked our own flight up and we're staying overnight at the Sheraton before returning the next day....much cheaper than the RSSC excursion)

Machu Picchu 2 night excursion

I want soooooooo much to see the Penguins and Sea Lions so I'm exploring different possibilities there.

Claudia, not sure if I'll take you up on on the Rep from H. Stern (I'll talk to Joanna about it). I don't want to buy any gems though. Thanks for your help!