Well lets distill the options a bit.
Personally I really like most Nikkor primes (apart from the 28mm which is crap), the 24 to 35mm lenses are all small, light, fast, sharp and cheap. I really like fitting a prime to my D60 - its small, lightweight discrete and fun package.
For wideangle usage, the 24mm isn't that wide on a crop camera. Its a very nice lens though, and is really good if you have plans to go full frame.
The Tamron 17-50 is a REALLY good choice here though as well.
Maybe you could have a look at your 18-200 images and find out where you shot the most - there is a program called ExposurePlot (
http://www.cpr.demon.nl/prog_plotf.html) which will go through your images, and tell you where you shoot. Perhaps this will help you focus on your most used range.
At this point, you are getting a lot of advice from all directions, most of it very sensible, but some of it conflicting!
So I'd be tempted to have a good long think, look at your previous usage and your preferred focal range, and possibily re-evaluate?