My husband and I stayed here in early April for two nights. I do not have status with Hyatt, but did contact the manager in advance, as we were celebrating our five-year anniversary. Piero was very responsive to my emails, and I could tell he wanted to do everything possible to make our stay memorable. Check-in was very personable, and we were personally escorted to our room. We had been upgraded to a room with a terrace! It was beautiful, and the room itself had great touches - adapters, tons of great amenities (e.g. bath salts and a sponge for the bath tub, etc...).
While the room was gorgeous, however, the service was impeccable, simply the best I've ever had. Just two examples - my husband had bought cough medicine one night in Milan. He'd left it on the bathroom counter - when we came back after a few hours out, we noticed the housekeeping had left a measuring spoon for him to take the medicine - WOW! So pro-active. Another example - we bought last-minute train tickets to Ravenna for the afternoon. Not only did Mario (the concierge) save me a booking fee, he also put together a packet with a train time-table, a summary of the area around Ravenna, the tickets, and some newspapers for reading on the train! He put this very-helpful packet together in less than 20 minutes, completely unbeknownst to me.
All that to say - while the Park Hyatt is certainly a beautiful hotel, what sets it apart is the service. Again, we do not have Hyatt status and we were treated like royalty. I cannot recommend it enough.