thisispants, there is a lot of attention being given to reciprocity failure in this thread, so here's an explanation.
Reciprocity Failure (more correctly, an effect) is purely a change in the film's characteristics outside its target exposure range i.e. exposures significantly shorter or longer than what the film is designed for will result in a loss (or gain) of contrast, loss of effective film speed and colour shifts (the longer the exposure, the more pronounced the colour shift). Time (shutter speed) and aperture (intensity) share a reciprical arrangement: if one is altered, the other must be compensatedfor the exposure to remain constant. But at long exposures, reciprocity occurs and the film's response is changed. Many photographers exploit this effect (particularly with Velvia and Provia)
Having done heaps of night (astro) photography, I'd recommend you 'give the film enough rope'. Provia 100F mentioned in this thread runs purplish at long exposures, and with a carefully chosen night scene (night skies, seascapes), this is an enhancement, not a fault. I'm also saying use transparency film rather than print film, and that also implies knowing your exposure and having some experience. I never meter for astro (or general night) scenes (they're all done on bulb, 45 minutes to 16 hours on Provia 100F), but in the bright lights of NYC, there'll be all sorts of conflicting sources of lights of all intensity, not the least being traffic moving toward you that can throw readings off. Perhaps do some 'test runs' near home and get the film developed and determine how well you did. Build up experience and plan the event. The thought just crossed my mind that an aerial shot (from a building, not a plane) looking over the night skyline would be good. Mmm!