Brazil -
~Definitely go see Foz do Iguacu on the border. That was one of my favorite things. Don’t go to the Uruguayan (gosh, how do you spell that?) town just over the border.
~I lived in Brazil for seven months and still don’t dare to go to Carnival. If anything, I’d go to Salvador… but then again, I like the previous poster/commenter’s idea of going to a samba school and watching some of the preparations. I did do that, and loved it!

Peru -
~ Are you guys surfers? I hear Peru is the new Costa Rica… I supposed if you are surfers, then you’ll already know…

I’m drawing a blank now… but I’ll try to make more recommendations if I can remember them.

- Torres del Paine is amazing. Probably the bests hiking of my life. The scenery is just fabulous and the refugios system (we did the W trek and stayed in refugios along the way) is great. We got lucky and had good weather most of the time, but the weather is quite finicky down there. Try to do a glacier trek while you’re there.

- If you like whitewater rafting, it doesn’t get much better than the Futaleufu River in Chile. A lot of people say it’s the best whitewater in the world. We went with Bio Bio Expeditions. The trips on their website sound insanely expensive, but if you call them up, you might be able to score a good deal (if they have open spots and don’t think they’ll fill them, they might give you a discount; you also might be able to get a discount by offering to help out, i.e. lug boats, cook, etc). Also, they only list week-long trips on their website, but, at least when we were there (2001), they would take day-trippers for I think about $150/day. It’s a bit hard to get to, but definitely worth it.

- We did Carnival in Brazil. I loved it, but I’m a city person and generally love chaotic environments. I will say that Carnival is much more than a drunken party. It is nothing like mardi gras. We saw surprisingly little public drunkenness. It was much more about the music and the dancing than I expected. We split up our time between Rio & Salvador, and really enjoyed both. If you go for Carnival, you must try to dance in the sambodrome with a samba school. It’s expensive (about $200-300 for the costume), but it’s a fundraising tool for the samba schools, and definitely worth it. If you go, I might be able to hook you with a samba school connection. I do think that Carnival is a gotta-experience-once type of thing (and I enjoyed it *much* more than other “gotta-go” parties like mardi gras and the full moon party at koh phag ngan). That said, if you really don’t like crowds and general chaos, you might want to avoid it. It is very crowded & loud & you will get lost & there is a general sense of craziness. And it’s not cheap. Plus, it’s not the “real” Brazil. I really want to go back to Brazil some other non-Carnival time to see more of the country. Everything shuts down for Carnival, so it’s not the best time to see the sites. If you have the time, the best of both worlds might be to explore Brazil in the weeks leading up to Carnival (I think it would be great to see the Carnival preparations; I’m pretty sure you can attend samba school rehearsals & watch them build the floats), and then just to stick around for the first 2-3 days of Carnival, to get a taste for it but not get too overwhelmed by the madness. There are also great Carnival celebrations in other parts of S. America.

- Buenos Aires is a lot of fun. Worth the visit.

- Not to add more difficult decisions to your list, but Colombia is wonderful. It’s overlooked by most western tourists (we only met 1 other American in our 2 months there), which makes it that much nicer for the people who do go there. The people are the friendliest I’ve ever met. They really are thrilled to have visitors to their country (they know the bad press it gets) and go out of their way to make it a pleasant visit. It’s got everything from great cities (Bogota, Medellin) to beautiful countryside (San Gil, Armenia), to some of the best beaches in the world (Parque Tayrona, Cartagena). If you are considering it & want more information, let me know.

Phew, that was a long post. Good luck making your decision! Btw, I’ve started seeing your blog mentioned on other travel blogs (most recently on writetotravel). Congrats!

Chile is the place to go.

As to the whole Carnival thing in Brazil, like you I tend to avoid those kind of things. Like Mardi Gras in New Orleans, which I’ve turned down the opportunity to experience, it’s just not for me. I hate big crowds and I particularly hate big crowds of drunk people. Oktoberfest in Munich was even a little too much for me and the World Cup in Kaiserslautern was just an all around unpleasant experience. On the other hand… it is a once in a lifetime opportunity and something that many people would love to attend. Certainly it would be interesting to see and a very cool cultural experience (if only there was a way to see it and not be surrounded by hoards of drunk people).