Hey!! im also holding onto a 1mth old D90!

And its also my first DSLR~
With regards to NR, i also nvr turn on when i took my night shots
And with ur shots, seems like u can reduce the exposure by abit imo...
I like #4, no PP meaning the light and dark parts were created by the lights from the tower itself??
But u might wan to cut off the tree peeking out at the bottom of the tower