I keep the Nikon 18-200 on my D300 at all times, but on my D700 I keep the Nikon 24-70. The 18-200 always seems like a compromise, especially in low light (I shoot way too much indoors in very poor lighting for work-related events). In bright light though it's hard to beat.
I have a collection of photos from Dubai with my old D200. This is the Burj Al Arab hotel from quite a distance away:
It's not as sharp as I'd like, and the D200 definitely suffered at 1600 ISO, but overall the lens worked well enough.