When taking portrait shots during the night, try not to use the auto mode on the camera. Otherwise it's likely the picture won't be very interesting. The reason is simple, the camera will engage the flash to make sure the focused person is lit properly, often over doing it, and in doing so many interesting background objects are washed out. Look at this photo:
Atlanta skyscrapers are in the background but you can barely see them. They are too dim and too blurred. Taking control of the exposure by lowering the shutter speed, combined with a smaller aperture to bring the background into focus, and higher ISO number to ensure enough light, I got this much more interesting picture:
If you are really uncomfortable with setting exposures yourself, at least try "Night Mode" (or called "Party Mode" on some cameras) or set your flash to "Slow Sync".