There are many relatively inexpensive hotels on the stretch of Lombard Street between the Palace of Fine Arts and Van Ness, and we have tried maybe a dozen over the years. The location is great for the Marina, Cow Hollow, Golden Gate Bridge, and the Presidio.
Good things about the Signature Inn: staff was friendly and efficient. Fixtures in the room were relatively new and worked well--TV, shower, etc. were very good. It was generally clean. Mattress was excellent.
Other things: the room was not carpeted, but had vinyl plank flooring. Small holes in the wall had been spackled but not touched up. The bathroom had a loose "barn door" that didn't provide much privacy. The hotel advertises free parking, but the internal lot is too small to accommodate all guests, and from the time we checked in to the next morning, there were no available spaces, so be sure to scout the neighborhood for street parking. The ice machine was out of order; a sign said "Sorry for the inconvenience." We had room 101, which was on the ground floor facing the parking; because there were no blackout curtains, only a set of shutters, it was impossible to make the room truly dark. Towels were clean but a little scratchy--which I don't mind--but mine had a hole in it, which was a step too far toward shabbiness.
Given the many similar choices in the neighborhood, I balance the small problems against price. Overall, it wasn't a bad stay.