I have written about waiting for and shooting after sunset before. So here I go again. Often the clouds can be lit very nicely after sunset. The contrast and dynamic range (different between lightest parts and darkest parts of the image) are much lower. This makes it easier for your camera's sensor to get the entire range of light in the shot without clipping (no detail in lightest and or darkest parts of the image) any part.

          You may still need a graduated neutral density filter to shoot to hold back the sky. The color can still be good even though your eyes cannot see it. Since the light is very low you WILL need a good tripod. I often shoot in quite dark situations. Just open up the shutter long enough and your shots will look good with good color.

          When the sun is set most people leave. This was also the case when I shot this image. It was shot the same night as last week's shot. You are there already. Just wait another 20 or 30 minutes. You may very well get one more shot. To get sharp and well composed images I setup and focus while I still have light. I set the lens on manual focus so that it will not change when it gets dark because then it is very difficult to focus again. Use live view or mirror lock up to eliminate vibration. Use your remote shutter release so that you are not touching the camera. These measures help you to get sharper images. The camera cannot be moving when you shoot at long shutter speeds lest you get blurred images.

Stay out just a little bit longer.