I stayed at both Palazzo Parigi and FS this year.

While I agree with the general sentiment that the FS is a bit tired, I still liked it. The location is a bit more central than Palazzo Parigi, with shopping right at the doorstep. At the same time, the leafy courtyard provides a quiet respite away from the crowds - that was for me the highlight of the hotel. Palazzo Parigi lacks such a space.

We stayed in executive suites at both hotels. The FS can be quite a bit less pricy than the rates quoted above if you get a good deal. I don't remember the exact rates, but I think I paid ~900 EUR for the executive suite, based on a 4:3 offer and a guaranteed upgrade at booking via a FSPP agent (and this was over Easter). Still a bit more expensive than Palazzo Parigi, but not much.

The quality of the hard product was actually a bit better at FS, I found, although a renovation/update would be in order. Our executive suite had 2 full bathrooms, a separate bedroom area, a dressing room, and a full size dining table. I would agree to calling it uneventful, but it was very comfortable, and we enjoyed having the space. The executive suite at Palazzo Parigi on the other hand was basically one large room. Nicely designed, with wood floors.

The quality of soft product was a bit underwhelming at both places, I felt. We had housekeeping issues at both places. Palazzo Parigi would leave my daughter's sofa bed as a bed during the day, so we did not have a sitting area. FS, on the other hand, would not be able to do the turndown service at the requested time, so we would return to the room after dinner and the bed hadn't been made (not what you want with a tired toddler, especially not if it's two nights in a row, and despite asking twice beforehand on the second night to make sure it doesn't happen again). Concierge, valet, etc. was fine at both hotels, but nothing stood out. I took the same picture of the bar at Palazzo Parigi, without issue :-)

I also stayed in some of the other Milan hotels previously. Given the debilitating traffic especially at rush hour, I feel location is of particular importance. I would not return to Principe di Savoia based on this alone - unless you have business in the immediate surroundings, I feel the location is just not good. My favorite is probably still the Park Hyatt. Yes, it's getting a bit tired, but the location is in my opinion unbeatable, and they have rooms/suites with very nice large terraces.

Also agree on the MO. Never stayed there, but have looked at all floorplans on the website. Bedrooms appear small even in the top suites. The only option they offer if traveling with family is two connecting rooms.