acflyer2 - Pay close attention to the weather. We just returned from Chile last Sunday and had intented to spend most of our time in the Lakes region - however, it was rainy the entire time we were down there (Puerto Montt) and there didn't seem to be any break in the weather. We were traveling on AA award tickets with the connecting Lan Chile flights included. Luckily for us, LA had no problems changing our return flights (without any fees). We flew back to Santiago and then traveled to Vina and Mendoza, Argentina. The bus ride over the Andes while long (6+ hrs) was awesome. The bus driver even let me sit up front in the conductor's seat and take pictures while the bus climbed to the Crito Redemptor tunnel. The bonus was actually seeing a number of Andean Condors soaring overhead.
I hope you have better luck with the weather - I will have to return in the future to explore the lakes region.