The only SA country I've been to that has also got very nice people was Brazil. This makes Colombia a country where you have to think about the safety aspect a bit before heading somewhere. On the upside, this also means Colombia isn't run over by gringo's yet, like Ecuador or Peru, which makes for a great travel experience if you're open to it. And the risks are easily minimised, luckily. As you probably know, there's a well worn gringo travel path that runs through South America.
Some people make it to Colombia as well and go on to Venezuela.
In Colombia, there's a typical gringo path as well. So just draw lines between these cities, stay on them and you'll run into your occasional backpacker. If you get of this path, you'll probably never meet a foreigner. There are lots of places worth exploring, national parks for example, or places around the Carribean coast. So when I have a week or so off, I just pick a national park or two, or a region that I heard good things about, and go there and explore.