Late response I know - but thanks for the info guys - very useful.
I am now going to spend most of my time in Columbia and Bolivia (so less up in the air) will do some trekking/hiking in both those places but I heard there was a place in Columbia north(?) of Bogota where you can climb and there's a climbers' hostel. I will be solo so hopefully it's easy to meet people to climb with. Anyone know anything about this?
Re flights - I am getting a round the world and it looks as though it's going to be cheaper to fly to LA and then get a side flight to Bogota via Miami. As soon as you go to places like Bogota or La Paz on a round the world ticket, the prices can go through the roof.