For about 70 days from August to November 2011 I traveled in S America, beginning in Rio de Janeiro, Brazil, and ending up in Lima, Peru. The GAdventure trip was divided into 4 legs (indicated with different colors on the map), with each leg going from one capital to the other, led by a different guide, and only some of the travel-mates carry over.
This was a “YOLO” trip, which means that both the moving around and accommodations were basic, and all of the travel-mates were between 18 and 40, most centering around their 30s. For most of the trip I shared a room with a fun and mature Belgium guy (who likes to pose seductively with inanimate objects); except for who you share a room with, there were few obligatory interactions, since people all do their own things at each destination. Most of the group was likeable. Some I really appreciated. A few I tolerated (too much drinking; derisive and disrespectful towards local culture; often both). (To be fair, I was getting increasingly agitated being around people all the time, and probably was unfun company for long stretches.)
All of the major moving around was done on buses, some public and others private, with about a total weeks’ worth of sleeping on overnight buses. The overnight/long bus rides were hit-and-miss in their comfort; the ones in Argentina were fantastic and a 22hr ride passes by quickly, whereas others smelled like feet or sewage the entire time. I think I was the only one to have gotten car-sick, and only twice.
The guides took good care of us. I thought they do a pretty hard job in trying to make everyone happy. Most were pretty knowledgeable; Jared, our guide from Santiago to La Paz, was extraordinarily knowledgeable. He was exuberant enough that for the first few days I though he was intoxicated. My only reservations is with the recommendations for food (too much conflict of interest to be objective). If you’re vegetarian you should especially check out Healthy Cow for other options.
Each leg was thematically different. It was all sun, sea, and sand in Brazil (red); snow and outdoors through the Patagonia (blue); desert and salt in Chile/Bolivia (yellow); and cultural-historical in Peru (green). There are exceptions, but overall I learnt and enjoyed the most from the latter two legs.