Well located to explore SF from
I was in San Francisco to celebrate my birthday, and was happy to get an excellent rate at The Serrano. The hotel itself was a great place to stay as it was well situated for exploring San Francisco, and had many, many easily accessible transit routes. I was able to take BART in from the airport, and able to take transit to go to the Japanese Tea Garden, Fisherman's Wharf, Pier 33 (for an Alcatraz tour), and transit to and from restaurants at night. The Serrano is within easy walking distance to Union Square, and all the shopping and dining that area has to offer. A quick trip down Taylor (be warned, it doesn't take a long walk to get into the heart of the Tenderloin) took us to our favourite brunch place, Dotties on several mornings. 
All of the staff was friendly and helpful, however I'd like to mention that the concierge named Stephan was amazing. When asked for walking instructions to the shops on Union Street (not Union Square), he suggested a great route along Polk where we were able to avoid marching up and down hills, and able to stop into a number of great shops along the way. When we complimented him on the excellent route the next morning, he told us it was his wife's favourite wandering route as well. 
Our room was lovely, and had a great number of electrical outlets. This might seem a strange thing to mention, but as someone who travels with an iphone, ipad, chargable camera batteries, and an ereader - it's amazing how many times I'm at a hotel with no where to charge my electronics without unplugging lamps, tv's or mini fridges! Way to go Serrano! :) The Serrano also placed me on a higher floor - which was much appreciated. A lovely view from the 16th floor. 
This is my 3rd stay at a Kimpton property, the other two were Ink48 in NYC and the Argonaut, also in SF. Of the 3 Kimptons I've stayed at, I'd rate this hotel as my second favourite after ink48. ink48 edges out the Serrano as the staff at ink48 went out of their way to provide me with a fantastic experience for my birthday last year (complimentary sparkling wine and pastries sent to my room, many suggestions of places to go celebrate, front desk recognizing me each time I came past, etc.); it was also my birthday when I stayed at the Serrano, and no special fuss was made for me. I guess this is the difference between a New York hotel, and one just about anywhere else in the world! :)
That being said, this certainly is a place I'd stay again the next time I head to San Francisco! The Argonaut is also fantastic, but as it's right on the Wharf, it is a little more difficult to manage as a base to explore the city.