South America bound?

I've wanted to travel to South America for about 20 years. It all started with a book about some fellow's walk across the Bolivian salt flats and a copy of Lonely Planet's South America on a Shoestring. I think that was the most expensive book I'd ever bought — hadn't started university by that point.

Seems like there have always been places that got in the way; the closest I've come was a trip to Costa Rica in in 2011. In the end, South America is always an option among so many wonderful, curious places.

Maybe part of the problem lies in my approach. SA is so big and so complex that any plan to "travel the continent" is doomed to fail. Where to start? How long to stay? Where to go? When to visit?

After two decades, I think it's time to narrow my scope. Maybe Ecuador, Columbia, Peru OR Bolivia. But wouldn't it be nice to visit all four as well as Chile, and Argentina, and Brazil, and...