This is what I expect from a St. Regis. A very new hotel South of Market that is tastefully done with excellent service. The whole place exudes a certain pleasantness and leaves you walking out saying "wow, that was a really nice hotel." Rooms were modern, clean and very nice. SPG platinum got an upgrade to an executive which had more space, a desk and a corner view. Lobby is well-done and cozy with a great bar and wonderful large gas fireplaces - I would be very happy to sit there for hours. Gym is nice and well-equipped.
Two minor nits: unlike Asian St. Regis hotels, the coffee in-room is not complimentary, and breakfast is a la carte instead of the amazing buffets I've seen at other St. Regis hotels, and not included with the room - again unlike other St. Regis. If you can swing this on your trip, do it.