I've only had two successful trips to Sutro at night. One was in October of 2005. The other was earlier this month (2006). On my last trip to Sutro I shot with Mark Jaremko. While Mark was conducting some side-by-side experiments to analyze dark frame subtraction on various high-end digital cameras, I spent most of the night reshooting a small cement staircase from different angles with a flashlight.
In the past, most of my gel-lighting night photography has been done with a hand-held flash. But over the past few months I've begun to really appreciate the advantages of working with a flashlight, instead of a flash. One advantage of the flashlight is that you can see how the angle of the light adds to or deletes the texture in the object (with a flash, I have to close my eyes and press the button, otherwise I'm blind for the next two or three minutes... I don't get to see the result until the exposure is complete). The other advantage of lighting with a flashlight is that I feel that I'm interacting with the subject. It's not quite as visceral as finger painting, but it's good enough to keep me entertained for the evening.
In the photograph above, the island in the distance is lit with the floodlights of the restaurant beyond the left frame. I lit the cement wall with a flashlight covered with a red gel. It took me a number of attempts before I found the best angle to point the flashlight in order to bring out the texture in the cement, without lighting up the standing area on top of the seawall. For me, the best part about using a flashlight in this shot was being able to control the amount of light on staircase in the upper-left.