Hi! Sorry for my late answer, I did not see your messages.
We are in Cartagena since 2 months now and it is great! We are having a very good time in Colombia!
We decided to spend 1 month in each country, here is our program at the moment:
July-August => Cartagena (Colombia) Done!
September => Lima (Peru)
October => Valparaíso (Chile)
November => Buenos Aires (Argentina)
December => Rio de Janeiro (Brazil)
Let me know if you are interested to join us somewhere!