You're absolutely right. The Virtuoso rate at the Principe di Savoia for that week end for a deluxe room with upgrade, breakfast, late check out and a 85 EUR voucher at the restaurant was at 320EUR; per night or 280EUR; for a week end rate without the amenities.
The Park Hyatt was at 580EUR or 450EUR with my corporate rate.
The FS at 600EUR, same for Armani and 650EUR for the Bulgari.
Even though I loved the PH, I would still opt for the Principe Di Savoia given the price difference. Unfortunately I still can't splurge all the time for every trip and am trying to put some money aside on a savings account for an Aman trip.