The Hop-on Hop-off bus is crucial for those who have little time in Santiago or who are afraid to get around by subway. It's a complete city tour that passes through all the tourist spots of Santiago and you can get on and off to explore each place from any point within the time of your ticket/day.
There's also a guided tour through a recording you can listen to as you pass by the places. You'll get the headphones and map when you board the bus. You can also download the bus app and track the route and how long it takes to get to your stop. The app has everything detailed: route, hotels, restaurants, malls…
The tour also includes tickets for the Santiago cable car and funicular.