I always like to look at the night shots with some light lines of cars or other moving objects. Making one of such photos is much harder task. Especially if it is the same moving object.
Trams in San Francisco are one of the cool tourist attractions and nice transportation. At night you have to wait for them a bit to come by and they zip by fairly fast. I think I tried to take the photo of at least two different trams and get something interesting. I probably could seat there and wait for another one, but we were tired and ready to go back to hotel.