South America for 3 1/2 months - Group Travel

I know for sure I am starting and ending in Quito, Ecuador, because that's where my return flight is from Toronto, Canada. Between there I have a rough idea. I plan to do Galapagos in mid-Jan, Machu Picchu at the end of Jan, possibly Iguazu falls by mid-Feb, Buenos Aires for a couple weeks and then fly down to Ushuaia and see if I can book a last minute cruise to Antarctica (which would be my biggest expense). After that, I would work my way back north through various parts of Patagonia and end up in Buenos Aires so I can fly back to Quito from there and head home in mid-April.
I'll write more details once I figure them out, but parts of this trip I will probably plan on-the-go.

South America for 3 1/2 months