Nice going with these night shots!
especially without tripod.
#1 is my favorite! I think the balance of exposure time is good as you have just enough light for all foreground, background and sky. The only advice might be to try and adjust the white-balance to tone down the yellows (I'd say this for all shots though).
For this shot, what caught my eye was the textures and the pale blue underneath the fountain.
#2 is similar and the moon is a nice addition. My opinion is that it feels a bit too tightly framed though.
#3 was a great idea but i guess a hard execution. The strong light from the on-coming traffic is kind of distracting
My best idea is to maybe try to take the same shot but at a less busy time, then you will be able to keep the same exposure time, to capture details in the sky, but avoid overexposing with too many headlights.
Tell me what you think... these are just some ideas though