I stayed at the Clift last year while in SF for a friend's wedding. I received an upgrade to a small suite, and it was absolutely lovely.
The hotel itself is situated right off Union Square, a popular shopping and tourist destination through which runs the classic Cable Car, a fun ride for tourists and a direct route to the Fishermans Wharf, on the other side of town. The location is perfect. The hotel is understated on the outside, I might have walked right on by did I not know where I was going. The indoor lobby is stunning, a dark retreat from the hustle and bustle of the outside city, indoors it is cool, romantically lit, and classy. The furniture alone is breathtaking and unique. The service at the front desk is very professional and classy, I was very impressed. Our room was ready early, and was spacious, light, and very pleasant.
Couples may wish to note that there are mirrors all thorugh the bedroom area, it created the illusion of space while seeming classy rather than garish. The bathroom, like all in SF, tended towards the smaller side, however it too was well appointed and designed.
I would stay in this hotel again in a heartbeat, but I might advise parents to steer clear if with young children, it is not a child friendly environment, from the sharp edges in rooms to the general "feel" of the place.