Thanks for the info guys. Our plans currently are to fly out of Spain to Montevideo, spend about three weeks exploring Uruguay, and then fly from Montevideo to Santiago. We plan to spend also three weeks exploring Chile, and we were thinking of gravitating to the south, so the recommendations have sort of confirmed that we might be on the right track.
The information about Colombia doesn't surprise me as riders from there have been in the top echelons of the big tour races for some time now, and the trickle-down effect of their successes is bound to have some effect on the enthusiasm of administrators to improve infrastructure for cycling.
I've had a desire to visit South America for some time, and our round-the-world trip has presented that opportunity. I am more a temperate climate person, however, so we probably will give those locations north the the Tropic of Capricorn a miss this time around. I am certainly thinking that based on the good things we have read about Uruguay in particular, that this won't be the last time we visit South America.