I stayed at the Marriott Santiago for a night in November of 2006. Overall it is a nice hotel. Large lobby, friendly staff, lots of restaurants, business center, etc. The rooms are good… above average for a Marriott... clean and comfortable… not over the top luxury (there is a Ritz in town for that). As Platinum I was upgraded to a corner business suite. This sounds good, and the corner part was, but the business part consisted of a room with a conference table and chairs. This is pretty useless on a leisure trip. Still my corner room was nice with a couch and the Revive Bed. The bathroom has a marble floor and a separate room for the toilet.
The concierge lounge on the 23rd floor was excellent. It was open on the weekend and it is open from 6:00am to midnight!!! Nice selection of snacks, deserts and a pretty good breakfast too (for a lounge).
For a leisure trip I did not like the location of the hotel at all. It is a LONG walk to the Escuela Militar metro. The Las Codes location is not at all pedestrian friendly.
Update: Spent another night a week later. They assigned me to one of the conference room suites again. I asked if I could get a regular suite and was told yes! Wow... much nicer. Full purpose built two room suite. The living room also was a corner room with windows on both sides. Nice view of the smog.

Massive bathroom with marble floor, two seperate vanities, seperate shower, large tub. Revive bed.
Still did not like the Las Condes location. Everything is car centric.