Last month we took a trip to San Francisco. My cousin moved there last December so we'd talked about visiting later this year depending on whether we could afford it and still had enough annual leave after Mexico. We booked the flights about 3 months in advance and paid around £300 each with Virgin. We thought this was a pretty good deal and it was, the only catch being we still had to add luggage on (£45 per bag each way) and could only select our seats 24 hours in advance of each flight. This is the economy light option they now offer and if you don't mind taking the risk it's a pretty good option especially if you only plan to take one suitcase between you like we did. The accommodation, however, was a bit more expensive for what we got and worked out around £900 for a week in a 3 star hotel in the centre. It was basic but a really convenient location so I would happily recommend it on that basis. It was called the Herbert Hotel on Powell Street.