In Colombia don't forget to go to San Agustin (archeological park in beautiful places and very quiet), El Chorro en Bogotà (great atmosphere, beautiful people, enjoy street artist), Zipaquira (near Bogotà, there is the Salt Cathedral) and Cartagena.

Colombia - Cartagena - It's a pearl of the Carribean Sea City. Historicaly, very strong city of Spanish colonialist. Visited by most of Carribean pirates in the Pirate Golden Age. Has amazing colonial architecture. The Old City offers plenty of restaurants, clubs and bars to visit. I've been there at 11'th of November, Cartagenian Independance Day - THAT WAS SOMETHING TO SEE ! : )

I think you couldn't miss the chance of passing by the Rio de Janeiro city. Maybe, if you have the chance, you should visit Brasília too. But if you are looking for more adventurous tracks, I would suggest you the pantanal, the royal road or even the northeastern semi-desert.

Visit a little town in Boyacá called Villa de Leyva - it's like going back in time 400 years. Stay at the Hosteria del Molino La Mesopotamia, and visit all the sites in that part of Boyacá.

In Colombia: Medellin (its simply amazing), the road trip from Bogota-Ibague_Medellin is very beautiful, Carrebean for sure (Tayrona for best beaches). I guess it depends what are you after. Dont be afraid to stay off beaten tracks, good information can be get i the hostels.

If you go past at the Caribbean of Colombia, make a excursion in the Tayrona national park. One comes either with the boat of Taganga there or with the bus of Santa Marta. The nights under palms and starlit skies are simply marvelous and on the day are beautiful the beaches there really breath-taking. Sorry for my babelfish-english ;-)

i can give u recommendations only about brazil as i haven't been to the other two ones (unfortunately)...as was mentioned, there's incredible amount of places worth seeing... out of those i've seen i recommend: rio-of course; iguassu-stunning place; paraty-peaceful cute town near rio + trinidade - beautiful beaches, near paraty; salvador - the culture, architecture,...; pipa - swim with dolphines near natal; ilha grande - the best beaches...and a loooot loooot more! but if u don't plan to spend there too much time, i'd skip sao paulo (the city is not nice itself, but the nights might be enjoyable especially when u stay by such a nice locals as i did;) ). enjoy your traveling and don't forget to try all the brazilian fruits and sucos (juices) made of them :)

As for Brazil - definitly don't miss Saquarema - I fell in love with this magical little town with beaches that you cannot see the end... And more fun if you're surfer ;) Other are Sao Paolo and, of course, Rio de Janeiro...

If you have time, you definitely have to go see Iguasu Falls. Or as they call it Foz do Iguacu. Simply breathtaking! You should see the falls on both sides...Argentina offers a spectacular close up view...

In Colombia....if you don't mind the trek go to Ciudad Perdida. Overall 6 days of hiking through the jungle to the Lost City - an experience you will never forget! ;)

I lived in Sao Paulo; the city never sleeps and the brazilian are too friendly; you don't need to speak portuguese... It was a magic city. Rio de Janiero was funny too. In Colombia, the people is very funny too and Panamá is very interesting for the channel. But, definetely, I would choose Brazil (food, people and places really beautiful)

Hey Sarah! I can only comment on Brazil, and there are LOTS of must-see places. If you want nature - the Amazon and Pantanal are a must. Rio of course can't be missed as it has an endless supply of highlights. My fave spot in Brazil though was Iguassu Falls. Be sure to spend a few days there!