We are going to Explora Patagonia in November. We decided that we probably would rather do trips to other places after this instead of go back to chile so we thought it would be best to see the capital of santiago in conjunction with Explora. To only go to chil once and see patagonia and atacama, or patagonia and valparaiso, etc but not see santiago would feel incomplete i believe.
We had an amazing time at Explora. Make sure you bring lots of layers as the weather changes really quickly. We had a pretty good snow storm just a few days ago and were hiking knee deep in snow. The staff is super accommodating however you really need to push them if you want to do harder hikes right away. They usually test you out and make sure you're fit enough for them.
We are currently outside of Vicuna. Unfortunately it is cloudy so not much we can do to see the stats. We are off to Pisco Elqui today.