The lens I use the most is my 35MM f/1.8 I would assume that 90% of those photos are taken with that.
The only other lens I use for night shots is my stock 18-55MM lens that came with my Nikon D5100.
I went to The Headlands in Mackinaw City Michigan a few weeks back and I tried out my cheap Rokinon 8MM f/3.5 lens and I got a ton of vignetting on all of my night photos. I was pretty upset..
I actually have been reading about night photography since before I got the camera. With my 35MM I am quite confident that I can get a pretty decent photo of pretty much anything at night with it lol.
My other lenses though I still need some work with.
I recently picked up an 85MM f/1.8 really cheap as well. I have not had a chance to use it though.
My D5100 has that cropped sensor so 85MM is actually like 100+MM so my field of view is quite small and I don't really like it for night photography. I am really wanting to splurge and buy really nice 14 or 18MM super fast lens just for my night shots.
I really wish I did more research on my camera before I bought it. I would have just splurged and went with a full-framed sensor. I am currently looking at the Nikon D800E, but that is probably a couple years down the road since the body only is 2+grand.
The rule of 600 is kind of hit and miss for me.using that theory with my 18mm I should be able to do 33 sec exposures before the stars begin to trail. If you look at my Flickr you can see some of the stars are just about perfect while others are slightly moved. I did however, buy all the parts to build a barndoor tracker. So the next time it is awesome outside I will be using this to track the sky so I don't have to worry about trailing.