Just about everything you read on tripadvisor about the Castle Inn is true. It is15mins walk down to F/Wharf or 15mins up to Union Square / Chinatown area. Simple but sufficient complimentary breakfast (coffee, good orange juice, yoghurt, fruit, pastry, cereal bars) left us satisfied (including 2 teenagers!). Stayed in the 2 bedroom-suite. A little noise from the street, and some noise from the ice machine just outside the room, but with ear plugs in (always travel with them!), had a good night's sleep.
San Francisco is an expensive city, and the Castle Inn offers excellent value.
Special mention to Varsa, the effusively helpful manageress, who provided all sorts of details about tours and transport. We could not have enjoyed SF as much without her help.
There is an excellent Thai restaurant - simple, fast service and great value - just 3 doors away for a convenient meal.
In advance of us arriving, we had asked Varsa to book us onto a city tour with Tower Tours including the Alcatraz tour, and I would fully recommend this, because you will get to see the slightly more out-of-town sights like twin peaks, Golden Gate Park, leaving you to explore the inner city stuff on foot later. Don't miss out Alcatraz - it is incredible. Our family really enjoyed US Pampanito too. Different!
If I was a millionaire I'd stay in a luxury hotel. But as a family, out sightseeing from early after breakfast until after our evening meal, the Castle Inn is absolutely ideal.

We stayed here in June 2008 as the first stop on a long road trip. We were not disappointed. The owners were on hand immediately with maps and directions. It was well rehearsed but nonethless a helpful introduction. The hotel is as is said on all the reviews in a great location and we walked to all the must see areas, *Do not miss Alcatraz by the way if you are in SF*. We stayed in a room facing the inner yard which was quiet . The room itelf was clean and well provided with coffee maker, fridge and microwave. Nothing is particularly new but this is not a problem. No complaints.

great place to stay quite yet close to everthing you would need for a site seeing trip. the staff are very helpfull and go out of the way to make your stay as pleasent as possible.rooms were clean and tidy with daily maid service. will stay here again if we return to san fran

Stayed for 4 nights in the 2 bedroom suite as the first stop on a trip down the east coast. Briliant location, busses run on the two streets either side(Van Ness & Polk), so transport links were great for any location. A three day MUNI pass for all above ground public transport cost only $18 so we used these a lot. Many nice places to eat on Polk street as well. Back to the hotel, reception was small but the staff were helpfull, the suite faced onto the street and did suffer noise, but heck you are in a city it never troubled us. The rooms were large, the beds comfortable, the shower was hot. My only critisism would be that the rooms and furniture were showing their age. In fact while we were there, a builder arrived to price up modernising the bathroom, and the staff said that several were being done soon. All in all location is the big plus for the hotel, i did see that Nob Hill motor inn and Broadway motel are very close as well but obviously i dont know what they were like, but they would also be located well.