Word of warning re visas, guys. Most guidebooks - including LP - and people in Bogotá (from my experience) reckon you can just show up to Migración Colombia (Calle 100 #11b-27) to extend your 90-day tourist visa. This has changed recently.
My experience: I showed up to a packed office - lots of Venezuelans trying to get their papers - only to immediately be told I had to go home and apply online with the new system.
http://www.migracioncolombia.gov.co/index.php/es/tramites-2016/3281-tramite-cedula-de-extranjeria
So, I did that but received no confirmation. After the weekend, with just two days to go before my tourist visa expired, I went back to the office and was fast-tracked to the front of the queue. A woman told me I would need proof of onward travel if I wanted to stay for an extra 90 days. She also said they never received my online application because the new system was broken :-/
She promised to help but asked I show proof of onward travel in a form of, at least, a bus reservation. I returned the next day after trying to RENT a ticket from flyonward.com (who had helped me previously but this time my ticket never came through - what a waste of money!) and after an hour of chatting with the woman, she finally said that I wouldn't need proof of onward travel. The sweetheart just extended my tourist visa for an extra 90-days.
But be aware, people. Apply online first and, if you don't receive a confirmation immediately with the new system, head to the office to talk it through. You're likely to be sent home if you do just turn up, though, having not tried to apply online.
Also - you can't pay via credit or debit card. To extend the tourist visa for an extra 90-days, you will be directed to a nearby bank to pay $92,000COP. Most people told me I could pay via card. You can't. Bring cash.