Accommodation
Renaissance Hotel
https://www.marriott.com/en-us/hotels/sclbr-renaissance-santiago-hotel/overview/
(15-18 min. walk to the meeting). For this hotel don't forget to mention the ISE meeting to get the discount.
If you have any questions about fees you can contact directly: marietta.vanetti@renaissancehotels.cl

Leonardo da Vinci Hotel
https://www.hotelleonardodavinci.cl/ (ca. 10 min. walk to the meeting).
I spotted a couple of apart hotels in the area which charge lower fees but after reading the reviews they offer very basic services for the fees they charge.