Starting life as a fog station in 1875, Point Montara Lighthouse Hostel is adjacent to the current lighthouse and has ramshackle yet beautiful Victorian architecture plus sea views to die for. There's a living room and decent kitchen plus a few private rooms for couples or families. Reservations about two weeks in advance are recommended, especially on weekends and summer.
Even if you're not staying at the hostel, you can visit the lighthouse grounds between 9am and sunset daily (but drop in at the front desk first). There's a whale-watching seating area and a trail to a small beach.
SamTrans bus 17 stops across the highway from the hostel.