Looking forward to Globe's response. That dude has been everywhere. And my thanks to everyone that's responded so far.
sorry - south america is the continent that I have traveled least on. but let me try
Chile- the trains are supposed to be cool, going up to the atacama desert by train is supposed to be cool. patagonia, of course. that would be number one in my book. I would try to spend enough time on the beach to really enjoy the seals and sea lions and pengiuns.
Osorno is suposed to be vey cool, in the lake district
Santiago is worth a day or two - there is a museum of precolombian, and the municipal market is cool, go about 10 am, spend soem time choosing your sea food and then get it cooked up.
san Antonio, on the sea west of santiago, very good seafood. there I have been.
Brasil - I've just been to Sao Paolo. if you do go, the municipal market is very cool, the food is very good, espectially the pizza, the steak resteraunts and the fajuada on wed and sat. I am guessing that the food in Rio is substantially different, but the people of SP are considered foodies. very hot women. the one thing that is cool to see here is just the overwhelming size of the city - it may be the biggest city in the western hemisphere (that or mexico city)
my wife has taken a cruise on the amazon and loved it
Columbia - there really isn't that much to see in bogata, but the gold museum is pretty cool.
Cartegena - I'd spend a chunk of time here. very cool old city. I would read up a little on fortifications, the fortificatins of cartegena are probrably the best preserved early modern fortifications (pre-rifled cannon) in the world. also a great old city. ride a chiva (a party bus, really a great experience. the beaches are pretty good.
santa marta - there is a cool national park here, and very nice beaches.
panama - take a canal cruise, that is awsome. if you don't want to spend the money, just go hang out at the locks for a few hours. honestly, the rest of the country isn't that impressive, and is a little seedy.
if you are including mexico in your trip, go to mexico city, also an awsome city. I'd hang out at girabaldi square one night, hit the late night toco places in contessa neighborhood, and get to the anthropological museum. the latter is good enough reason to get to mexico. the pyramids just ouside of town are also worth seeing.
have fun. If you end up going to any of the specific towns I mention, let me know and I will get you resteraunt recomendations.