Shooting ramps at night in as far as the color correction is tricky. Forget print film, but if you really feel the need to shoot print, then scan from the neg, then you will have overall control of what your image will look like. Slide film is a whole diffrent animal and lot more suspetable to color shifts than print film, simply because these is no printing process.
On the ramp, you have a lot of diffrent lighting sources, Flourescent,Tungtsten,Quartz,ect.. Carrying around a slew of filters was needless to say a pain in the ***, thankfully something called Photoshop came along a few years back and freed many of us from the hassle of figuring which filter is right for which lighting source. There are still a few perfectionists out there who will go to all that trouble, but frankly I do not have the time. You can always do what Chris suggested, look for an area that looks 'natural', but keep in mind what looks natural to your eyes may not be what you see on your final image. Even Chris's 2 excellent examples are a tad green, due to the florescent lighting.Remember that florescent lighting looks natural to the human eye, but will leave a greenish cast on a slide. Again Photoshop, or most other imaging programs will solve these problems.
"Show me the Braniffs"