Hi Nick,
The buildings look a little soft to me and not that sharp. I see that in your first shot you have; f/10, 30sec, ISO 100, and in your 2nd shot you have f/2.8, 3.2sec, ISO 100. Try a compromise of all of these settings; to increase your ISO, stop down the aperture, and play around with the shutter speed.
If you leave the shutter speed at 3.2sec, then I would try to stop down to f/8 and increase your ISO to 800, or f/5.6 and ISO 400, or f/6.3 and ISO 640. Some people don't like partial ISO's but I don't seem to notice a difference.
If you lower the shutter speed to 2sec, then maybe f/8 ISO 400 would work. I'm hoping that the the higher ISO would allow you to use a smaller aperture to increase DOF and sharpness in the buildings. Make sure that your focal point, AF spot is closer to the buildings or on the buildings since it won't really matter if the dark water is OOF.
What kind of Body, Lens, focal length, and Tripod are you using?
Other things to consider for increased sharpness would be the 2 sec timer, shutter release cable, or mirror lock-up. Add weight to the tripod to increase stability. Get a hook and hang your camera bag on the hook.
Also be aware of the time of evening that you are shooting as well as reflections on the water.
I agree with the others regarding composition. When you are composing the shot, take into consideration the amount of water and clouds in the photo (rule of thirds), as well as the size and balance of the buildings. In this case since the clouds and sky are more interesting then I would include more sky and less water like Brant has suggested. The tallest building does not have to be in the center of the photo and if you see a nice balance between short, fat or strong looking buildings on the edges of the frame then that would be a good spot to cut off your composition. A zoom lens can work well for this when you can't move forward because of the water. Sometimes zooming in with less buildings can work too.
I also like Erno's suggestion of finding a foreground object to draw the viewers eye into the shot. Sometimes I find that wide angle focal lengths, can push the subject too far back int the frame and then the viewer can become detached from the subject.
Rich