A great vantage point and a little cooperation from the elements is the key to photographing great cityscape photos.
One the easiest ways to locate great locations is to use Google Images and study the "Points of Views" (POV) and conditions those images were made under. This provides a general idea of what other photographers are photographing and some of the different POV's they are creating.
Knowing when to shoot in the San Francisco Bay Area is tricky because most of the time it's foggy, overcast and unpredictable. Therefore it is a good idea to follow the weather sites, like weather.com or Google the weather for a particular location to get an idea about how the conditions might be trending for that area.
Photographing cityscape depends on skill sets, the type of equipment used, and vantage points considered. Landscape photography is one of the most complex areas of photography because there are a lot of technical layers to making and image "Pop." Before photographing an area; make sure there is a clear understanding on how the natural elements of that location, such light or a lack of it, smog, haze, wind, trees and obstructions will affect your photos outcome.
Here's a reality; to make one great photo most photographers will visit the same location locations several times.
The following images were photographed for my Project 2212-13. I have visited this location at least 5 times over the last 2 years.