The lenses of choice for weddings are the 24-70 f/2.8 and the 70-200 f/2.8. If I had to have only one of those I'd go with the 24-70 f/2.8.
If that's going to give you sticker shock Tamron makes a 28-75 f/2.8 that is superb for around $500 somewhere, although I'd prefer the Nikon first and foremost.
MLeeK couldn't have said it better! The 24-70 f2.8 is very versatile. Now, I know the Nikon 24-70 is a little more than what us Canon guys will pay, but its worth it. I currently own the Tamron 28-75 f2.8, and its wonderful. Not as good build quality as the Nikon or Canon of course, but the image quality is great, especially if you need the lens now. Its $400-$500 depending on where you buy it from. Good luck!