Santiago Day trip or Overnight
 

I'm about to go to Santiago for business. It's my third time there - I've already been to Concha y Chinas (private tour), Valparaiso and many of Santiago's highlights. I just found out that I have a free weekend - two full days before my flight home late Sunday night, and I'm thinking of going to hot springs resort or on an organized day trip. Any suggestions?

See if you can get something to Termas El Corazón or Jahuel if you want a relaxing spa weekend. Both about 1.5 hrs from town.
http://www.termaselcorazon.cl/
http://www.jahuel.cl/

Cascada Las Animas is up in the mountains of the Cajón del Maipo:
http://www.cascada.net/index_ing/index

This takes longer to get to, about three hours, but is very relaxing and gets you right out of Santiago.
http://www.tumunanlodge.com/lodgeng.htm

Thanks. Just checked the weather and it might be too warm for hot springs. However, it seems to be in the low 60s F at night. Do I need a light fleece or light leather jacket?

A light cardigan would be enough, but if you are traveling with a light fleece that would be fine. The temperature is usually very pleasant in the evening.
Both termas have outdoor pools as well.

Thanks so much for your suggestions. I ended up staying in Santiago because it turned out some friends were going to be here, so I didn't get to the hot springs. I did do the free walking tour, which was an excellent snapshot of the city - culturally, politically, visually...and great exercise. Learned more about Chile in those three hours than in two previous visits.

Nice that you enjoyed the walking tour. It's good. You can do the termas next time.

Next time try the bike tour through La Bicicleta Verde or the Santiago Running Tour if you want to get even more athletic!