When I travel with my D300 I just bring along the 18-200 VR and perhaps a 50mm F/1.4 for low light. The 18-200 VR is fairly lightweight. If you have decent light at all, it gets great photos without the weight and hassle of carrying and changing lenses all the time. The VR makes it possible to get good results handheld, at night, if you are in an urban area. For better image quality and low-light usefulness, while retaining the flexibility of a zoom lens, I have a set of pro F/2.8 zooms (11-16mm, 14-24mm, 24-70mm, and 70-200mm) - boy, are they great! And boy, are they heavy!
You can get rid of the complex distortions found on the 18-200mm VR lens with DXO Optics, the software is amazingy powerful and simple to use. It can also do some great stuff with bringing out detail in shadows. It won't make the 18-200 photos look exactly like they were taken on a pro lens, but it is a lot cheaper than buying a set of pro zooms.
Edit: added an example handheld nighttime shot with the 18-200mm VR zoom, as shot, resized to 800x531. Nikon D300 1/30sec F/5 70mm
Auto ISO chose 1400. That means there is some grain/noise visible if you like to pixel-peep.
The VR feature is perfect for low-light shots of stationary objects.
http://www.flickr.com/photos/31055544@N05/4124482794/