In my opinion 6 weeks for 4-5 countries in Latin America is not sufficient and you will force yourselves to "fly" through things and end up not experiencing it to a full degree. You are trying to cover too much in a relatively short time. I would rather pick 2-3 max. and enjoy it. If you focus just on South America I would even narrow it just to 2 countries since they are way bigger than their Central American counterparts.

If this can be of any help, few advices:

• Try to learn at least some Spanish if you don't speak it since people in many parts of Latin America don't speak English especially if you get to rural areas or off-beaten-path places. In a long run it will save you some money and you will have more fun. Not even mentioning that many times you will get into situation where your guide will speak only Spanish so you will end up not enjoying it so much or being someone's liability.
  
• If budget is of any concern to you, try to avoid Costa Rica and possibly Belize since these are the most expensive and Gringo infested (especially Costa Rica). Not that they don't have anything special to offer, but I found other Latin American countries to be more of a cultural experience and on an adventure side.
• If you really want to stretch yourselves over 4-5 countries in such a short time, consider flights in between major destinations from time to time. In some countries like Ecuador land transportation can be a nightmare and you can count on spending 10h on a 300km bus journey.
  
• Places to explore ancient precolonial civilizations would be certainly Guatemala, Belize and Honduras in Central America. I really liked Yaxha in Guatemala which is not so far from famous Tikal National Park. Way less crowded with tourists and with amazingly preserved pyramids. In South America Ecuador, Peru and Bolivia when it comes to Inca empire, but even if you want to see some cool stuff, go to San Agustin in Colombia where not so many tourists set their foot to see some amazing precolonial culture statues.
  
• Central America is more of a beer and rum region, if you get a chance try Flor de Caña rum in Nicaragua, but don't go for less than 7y aged. Wine is more of a domain in Chile and Argentina.
  
• When it comes for prearrangement for some of your activities, in some cases it might be necessary because they are popular, but in most cases I didn't bother and did it once I got to my destination. If you are staying in hostels, they usually have very good idea what you can do and explore in the area. Definitely better than hotels. So even if you are staying in hotel, try to visit few better known hostels in the area to see what they have to offer since their trips and activities are usually cheaper and more adventurous.
  
• If you like beaches and looking for some secluded places consider Corn Island in Nicaragua or Kuna Yala in Panama, both on a Caribbean side. Pacific side is more of a surfer paradise since Pacific tends to have bigger swell than Caribbean Sea. Some cool surfing spots are San Juan del Sur which is as well quite close to Isla De Ometepe where you can easily spend few days on an island hiking and relaxing.
  

Well, if you have any questions feel free to ask more. If you want to get better picture about some countries mentioned here you can take a look at some of my collections well sorted out into albums based on region.

Hope this helps a bit and have a great trip guys!

I suggest visiting Cusco and Machu Picchu. An amazing, unique place in the world. If you like the sea you can visit in Chile, Viña del MarThe best time of year is March, October and November. Patagonia (Argentina) and Torres del Paine are also two very beautiful and interesting places.

Hi! If you love beaches, Costa Rica offers plenty of options. I would suggest both the Caribbean side Limon or the Pacific side, Nicoya. One of my favorite is Playa Santa Teresa especially for those who love surfing (or a quite/local type beach).  Osa Peninsula is also a very unique place even though it is a bit complicated to get there. (let me know if interested to provide further details). Another recommendations of quite local towns (besides Santa Teresa), are Las Catalinas, Punta Islita or Monteverde.

However, speaking about beautiful beaches in Central America, I would say that Roatan is also magical, especially for diving. The Copan ruins are also another interesting site to visit. If you are interested in something more cultural I will recommend Antigua Guatemala

A city with good nightlife is: Bogota which offers really nice places for dining out,  dancing and meeting interesting people. A few examples of these sophisticated places are Park 93, La Candelaria and a restaurant very unique and creative, located in the Chia area is Andres Carne de Res.

I hope this information can be of great help for you guys! Enjoy the ride!!

Pura vida!!

Since you only have 6 weeks to travel, I would recommend staying in Central America the entire time. Travel time between countries is obviously way less time consuming than South America, and it's more affordable. You also get to experience an entirely different culture each time you cross a border, which makes for a fun and interesting travel experience.

My favorite beaches are in Nicaragua and Costa Rica. Try the beaches near Tola in Nicaragua, most notably Popoyo and Playa Gigante- they are less crowded, absolutely beautiful and full of locals and surfers. In Costa Rica I prefer the beaches near Nosara, Garza, and Playa Avellanas- once again, less crowded and more of a local beach culture.

If you like Mayan ruins, you have to go to Tikal National Park in Guatemala. That is an experience you will never forget! Find a knowledgeable guide and go super early in the morning to avoid the crowds and the heat.

Overall, I would recommend starting north in Guatemala and ending in Panama. You could also fly into Cancun (they sometimes have good flight deals) and travel from there to Guatemala.