Back in 1964, a gentleman by name of S.P. Martin took the trouble to develop a handy little "Nighttime Exposure Calculator." It was first published in Popular Photography. The calculator provides the proper exposure (f-stop and shutter speed) depending on the set ISO, for about 26 specific common "scenes." These scenes range from: Fireworks, brightly lit night baseball games, bright moonlit landscapes, dimly lit subway stations, Manhattan-like cityscapes, even Niagara falls at nite....etc.* In recent years it has been modified to make it more suitable for digital work. I have used it for night scenes probably since its original publishing and I have found it reliable to establish an exposure starting point.
You can download it at http://www.stacken.kth.se/~maxz/files/jiffy.pdf. I suggest you have it printed at a Staples on high quality white card stock, then cut and assemble. It's easy to use, once assembled.
An example for your photo might be scene 6 which is for "Broadway−type, brightly lighted Main streets. For emphasis on reflections of rain−wet streets, use Scene 6." Again, just a starting point so don't forget to bracket.