Park Hyatt or Excelsior Gallia Milan?
I would say that the PH Istanbul ranks as one of my favorite, if not most favorite PH. Great rooms, excellent service, we loved the area that it was in. The PH Milan stay was less satisfying. The rooms are nice but not great. We did probably get the worse room in the building (Accessible by the elevator) We had trouble with our coffee machine and our safe during our stay, which the management did handle ok but was just annoying. They literally could not find us another coffee machine in the entire hotel but did comp all our coffee through room service. The location is excellent for seeing all that Milan has to offer. I do not recall of the AC goes to BHrubin levels. I had some trouble with the concierge who apparently only could get me tickets to the last supper if I bought a city tour package from them. I was able to find tickets through an online reseller at a minor markup pretty easily. All and all a hotel that's worth using points at but I wouldn't spend $$$ for. (For reference I did spend $$$ at the PH Istanbul).
Sorry I don't have any insight on the Excelsoir.
Fdw