I have the 18-200. The quality is a bit worse than the 18-105 and it has creep issues, but it is brilliant as a travel lens when you don't want to pack and change multiple lenses.
The nikkor 18-200 vr costs about 1000 sgd. Your likely alternatives are Sigma 18-250 OS and Tamron 18-275 VC. I believe they should cost a bit lesser than the 18-200 but give longer zoom. They are a little slower to focus though.
If you don't need the range, the 18-105 and 18-135 are good lenses. The 18-135 is not VR though. The other option would be the 18-55 + 55-200. Barring the 18-55, the others are around 400-500 sgd.
My experience with the 18-200mm is highly positive. To me it is very versatile & sharp & is a fantastic, awesome walk-about lens, all things considered. It is subject to distortions at the extreme ends that's typical of many zooms & limitations in term of smaller aperture. If you are more into tele than wide, than the 28-300 would definitiely be a better choice at a slightly higher cost.
Just using 18-200 lens for about 1-2 months, above average. We cant find a perfect lens in full range. 1 thing i am very suprise in the focusing responds. Compare to 18-55 it is still faster, it is common when switch to live view & test it. Some time i face difficulty in focusing for my kit len. But this zoom len is good. I am aiming for 35mm F1.8 now.....
18-200 is brilliant as just a single lens to carry for travel. But having said that superzoom lenses usually have quality compromises to achieve the ~10x that they do. This lens is no different. If you need best quality and are willing to swap lenses more on the field (which can sometimes be dusty) or don't need the tele to 200, there are much better lenses out there.