Right now, Amex Platinum (Canada) is giving (for the balance of this calendar year) a promotion whereby if one stays 3 nights, the third night is free (for any Hyatts around the world). However, if one stays 6 nights, one can only get 1 free night.

I am thinking perhaps of staying 4 nights at Hotel Principe de Savoia when attending the conference, and perhaps 3 nights at Park Hyatt Milan, when staying for sightseeing. Both Hotels would therefore be booked through the AMEX Platinum travel agent - both hotels are considered to be AMEX's preferred hotels.