Really I don't like too much Santiago, it's very stressful and have a lot of smog, but if you forget this things really you can pass funny.
The things I like about Santiago is the streets and the buildings, I like the streets because when you up the bus, you can discover new places only see by the window, and if you take the wrong bus you lost, this is very funny I lost a lot of times in Santiago, but ever I can find the right way, the buildings I like because this is higher and have a very beautiful architecture, specially the new buildings, and Sanjatan, its my favorite, all the buildings are contructed with glazes.
In Santiago you can do a lot of things, you can go to the museum, go to bellavista street, go to the zoo, go to the hills, Saint Lucia or Saint Cristobal, or take a bus of Turistika and travel the more ancient and the beautiful places of the city.
If you visit Santiago I recomend visit, the aim square, is surrounded by ancient buildings, and too visit the hills and go to the bus terminal because I don't believe that Santiago is a city to go of vacations, I believe that Santiago is a city to leave and work, but not to visit, because is stressful, and the people be very pushed for time, always late, for this you take a bus and go Buin, Lampa, Pirque, Cajón del Maipo, and return to Santiago to eat and sleep.