QUOTE(kmm514 @ May 22 2008, 05:10 AM)

We want to travel through Brazil, Uruguay and the northern part of Argentina.
Arrive in Rio De Janeiro, Brazil and spend 2 nights and 3 days in Rio (what should we do in Rio? where should we stay?)
travel to Iguazu Falls, the Brazil side, take the Macuco Boat Safari, spend 2 days and 1 night here (do we need a visa to go to the Argentinian side, so we need a visa to travel in Brazil?)
Once in Montevideo, rent a car and go to Punta Del Este and Colonia del Sacramento, spend 4 or 5 days traveling around southern Uruguay (is there anything specific we need to do in Uruguay? like a must-see? any suggestions would be great!)
KMM514
Sounds great!!! I did some of this, but not all. If you're landing in Rio with a family, a lovely place to stay is Santa Teresa. It's not on the beach though, it's the old town with cobbled streets etc, but lovely, and you can ride the tram and visit the stairs of Lapa easily. You can get to the beach easily though. If you want to stay near the beach, I'd recommend Ipanema with a family. I lived in Copacabana for 6 months and loved it, but just don't go about with any valuables on show, especially if you're just off the plane - you'll stand out as a target for a thief. Don't miss the Christ statue (closes at 5pm, so this is for the daytime - great view of Rio!) Then the Sugar loaf mountain, which I'd recommend at sunset, as it's another view of Rio, but at night, so different as well! There's a massive market in Urugayana that you can get to on the train, and if you like football, the Maracana stadium is the biggest in the world and the atmosphere is immense. I love Rio!!
I didn't do the Amazon, so can't help with that, but the falls are amazing. You can do the Brazil side in a couple of hours, as this gives you the Panoramic view, but you need a whole day for the Argentinian side, as there are trails over/under/on the side of the falls, and you can go on a boat trip that takes you right to the falls, that's not for the faint hearted!!! You can get a local bus from the Brazil side to the Argentinian side for 50cents each. The buses are obvious - they say "Puerto Iguazu and Foz de Iguacu" on the front. They drop you at immigration on the bridge, then you get on the next one with the same ticket once you've passed security. I don't know where you are from, but with a UK passport, you get your 3 month visa while crossing the border in all the South American countries I was in. I crossed that border with a South African and Irish person, and all of us did the Visa at the border - at no cost either.
If you want to take in the north of Argentina, I'd recommend going from Puerto Iguazu (Argentina), to Salta. You can go direct on a bus - long journey, but not sure about flights. Salta is lovely!! You can then go direct to Mendoza, where the wine is cheaper than water, and the meat is gorgeous (and v. cheap as well). From Mendoza, you can head for Buenos Aires. I know you wanted to go here last, but you can just bypass it and get the boat to Montevideo from there, then do all your sites from there. Everywhere you mentioned in Uruguay is in the south, so that's why I'm suggesting doing it this way. You could find out if you can hire the car from Colonia del Sacramento, as you can get the boat from BA to there, then you won't have to go back on yourself. Just head round the coast, then when you're ready, get the boat back to BA from Montevideo?
Hope that's helpful. My blog address is www.travelpod.com/members/kathryn77 so you can see the attractions I saw in Uruguay. You'll see I didn't do it the route the way I've suggested to you, but I know you can, and that would be my recommendation if you have just 3 weeks. If you have any more questions, feel free to ask