Oh, I should have also mentioned I like the composition in that second photo as well. The building has a cool sort of dual personality going on, but the traffic light in the right half keeps that part of the image from feeling 'empty'.
As far as camera settings there, your exposure was at 5/8" which is in the danger zone for losing sharpness due to mirror slap. Just before the photo the camera raises the mirror extremely quickly and this can cause some minor vibration in the body. In my experience I've seen a little loss of sharpness between 1/30" and 1/2". I would recommend shooting in an exposure delay mode which raises the mirror, pauses, and then trips the shutter about half a second later. This helps your camera settle down before recording an exposure. With good camera setup discipline you can safely move into much longer exposures.
An approximately equivalent exposure for your second shot would have been f/8, iso 200, 15" shutter. As long as your tripod is solid you would end up with a much cleaner shot that way.
As for the color - for night shots definitely shoot RAW. This allows you to adjust the white balance later. Create the best mental image of the scene that you can, then when you're sitting in front of your computer tweak it to look the same. Sometimes a
slight yellow cast lends more realism to a nighttime city shot.
Another excellent exercise is to set a manual white balance. Refer to your manual to see how. Bring along something that is a neutral tint; most photo stores sell grey cards that are perfectly neutral. On the other hand, I often use a white piece of paper or anything else white I can get my hands on. People will ridicule this approach saying that paper can have a slight color cast to it that throws off your shots but I've often found paper perfectly adequate for architecture or cityscape shots at night where everything is so far off anyway that you're getting much closer to reality if you have something that's "pretty much white". You could also try the tungsten or fluorescent settings on your camera and see how those look.
Here's a shot I took - longer exposure, lower iso, smaller aperture.