When DS was 21, he did a 10-week internship in San Francisco. He stayed at the Monroe Residence Club in Pacific Heights, 1.5 blocks from the start of the California cable car line.
http://www.monroeresidenceclub.com/index.html
DS rented a private room w/shared bath. Included in the price are breakfast and dinner, Monday-Saturday, and brunch on Sunday, plus some maid service (not daily, but I don’t recall the details). Secure entrance, an international mix of residents. DS said he would stay there again if the timing was short like his was. A friend of DS had use of an internship-provided condo in the Coit Tower area, but friend was jealous of the meals that DS got with his rental. Like housing, food is also expensive in SF.