While I'm only going by recollection, here. I don't believe the W Santiago is close to any subway line, although I can confirm that taxis are relatively inexpensive. If you want a definitive answer, you may either wish to call the hotel directly or Starwood who will either have the information or call the hotel for you. On the topic of taxis in Santiago, do not agree to pay a flat fare for any trip you may be taking. Rather insist on paying the metered fare. Flat fares will invariably be higher. This is a common trick used by drivers to maximize their fares from tourists.

The subway system in Santiago is great by the way. Although it doesn't encompass a huge number of lines, it covers most areas you want to see and is cheap (less than 90 cents a ticket) well run, clean and safe.

Although the W Santiago has received great reviews for its facilities and service, it does not appear to be strong on location. On the other hand the Four Points Santiago is just that, a Four Points, meaning your staying at a far more downscale category of property (although location-wise it is the best of the 3/4 Starwood properties) .

I personally prefer the Sheraton / San Cristobal Towers for a balance of location and facilities. The walk to the closest subway station (about 10 - 15 minutes) across the river in Provedencia doesn't bother me and I've found the Sheraton's room rates to often be very close to the rates being charged at the Four Points.