In post #90, I mentioned that Wife and I really liked the Diana Majestic, and were treated extremely well during a pre-Christmas shopping trip. Cool bar, good restaurants nearby, and close to shopping. Staff was amazing and everything was decorated for Christmas. Was upgraded and treated like royalty as a GM from another hotel asked them to treat us well.
I stayed alone at the Meridien Gallia and received a large room, but the hotel was a bit run down and the area was not great. But very convenient if you need the train station.
Have not stayed at the Westin, but it is in a good area and looks quite nice. It was not available when we stayed at the Diana Majestic. If it is like the Westin's that we stayed at in Florence and Venice, I would go for it. But the Diana, though a Sheraton, was nice.
Good luck.
fduvall