Thanks EG - that's very useful to know. Some of the links seem to be broken, but I'll navigate about the sit and see what I can find. It all seems quite daunting though - and I will definitely have to wait until my Spanish is better.
I'm off to BsAs again in a month, and plan to have a sniff around for some GA, so I can get my spotting fix if nothing else!
Dan Dare - I envy you that trip to Colonia. It's spectacular enough to arrive there by Buquebus!