My teenage son and I stayed at Castle Inn on a trip to San Fransisco. It was very close walking to many dining options as well as close to a convenience store to buy snacks/water to keep in the hotel room. It was also about a half hour walk to Fisherman's Wharf for a number of activities (like tour boat ride around the bay and Alcatraz tour) as well as many stores for shopping.
Castle Inn provides parking, which was very helpful. There is a lower parking area beneath the hotel and a lot above ground. I only parked in the basement and found it to be very small and tight to manuever, so having a small car is certainly recommended.
Our room was also on the small side with a small bathroom. With only two travelers, we managed fine, but if you're traveling with more people it could become cramped. Otherwise, the room was clean and offered everything we needed for a 3-night stay.
The area is a little noisy being in downtown of a major city; however, one night was pariticularly bad with what sounded like street racing, luckily that was just one night and didn't last too long.
The gentleman that checked us in was friendly and helpful providing a map with tips on where to go for food/stores.