The wide angle lens is the best thing to use to get good shots of a large cityscape such as the NYC skyline or the Golden Gate Bridge. This will help capture all the important elements to get the scene right. Pay close attention to the foreground in the viewfinder, to ensure you get the shot you want.
As mentioned before, the lines in an image curve with a wide angle lens. You can use this distortion to add amazing effects to your images. You can also eliminate as much distortion as you want to by ensuring you are pointing the camera completely straight ahead.
The Sky Is Your Friend
When using a wide angle lens for nature photography, make a large portion of your image the sky for a very interesting effect on the image below the sky.