Hard to top this place. I travel regularly for business to SF and there is no hotel equal to this (this includes my stay at the much more upscale and expensive Mandarin Oriental).
For starters, the location is ideal for business travelers (it's in the financial district) and vacationers (stayed with the family here). It's just a few steps away from Chinatown and the cable car stops right outside the hotel.
The hotel is stately but warm. The rooms comfortable, well-appointed, reasonably spacious, updated and clean.
What makes this hotel is the service. I have double digit stays here and am still awaiting my first unsatisfactory service experience. To the contrary, I am consistently wowed by the excellent service. Everyone from the doormen to the front desk personnel to the concierge to the cleaning personnel are genuinely friendly. It renews my faith that good customer service and well-run businesses are not dead!
I even had one trip where the people in the room next to me clearly had too much to drink and were quite loud at midnight during the week. Noise levels are usually excellent here, so I had to call down and ask them to stop by the neighboring room and ask them to quiet down. That was done in minutes. To top it off, the hotel sent me a personal note the following week apologizing. Apologizing for events outside the hotel's control stands in contrast to many hotels that seem irritated to fix things within their control.
Stay here. You won't regret it.