I'm not entirely sure how the 18-200mm f/3.5-5.6 became the lens of choice for the D300, as it's... rather weak. I own one and use it when I know I'm not going to be able to change lenses for days at a time (e.g. road trip, traveling), but it would not be my go to piece of glass.
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Obviously, another solution would be to get a lower end body and higher end glass, which I'd find to be a bit better of an idea. The 50mm f/1.4(/1.8), 24-70mm f/2.8, 70-200mm f/2.8, and some sort of wide-angle lens (tokinas are good and nikkors are good) are all lenses that are good to have at your disposal, despite the fact that people will think you're aiming some sort of weapon at them.
But right. Use the 18-200mm as a jumping off point, not as a cure-all.
Let's accept that the lenses you mentioned are desirable - indeed they are. There may still be a reason to go with the D300 + 18-200, depending on how advanced a photographer you are. If you are a newbie, then I'd argue it makes sense to stick with the 18-200 for some time until you not only learn your camera and some of the possibilities of digital photography, but the tremendous range will allow you to find your favored focal lengths and your favored photography (portraits, sports, nature, social, architecture etc.). At that point, you can make a much more informed choice of which lenses to buy.
There is another reason why shooting with the 18-200 makes sense - time. All the lenses you mentioned have issues. The #1 issue is availability - take the Nikkor 24-70 2.8. This was going to be the first lens for my D300. Unfortunately, it just wasn't available anywhere. Now, hunting diligently for weeks/months on end, I'm sure I could buy it - but meanwhile I'm glad to have a lens to shoot with - the 18-200. The other issue that immediately cooled me in my zeal to get the 24-70 is the fact that this new lens may have some teething problems. There are tons of reports from reliable photographers about horrendous sample variation - in fact, many find anywhere between one in two to three in four lenses unacceptably flawed (back/front focusing etc.). This is a great lens... when it works. Here's my plan: wait until the 24-70 is widely available - at which point they may even work out some of these teething/production problems, or at least it will be easier to send back and get a new copy until one is actually working... without a good supply, you can't do that. Meanwhile, I'm shooting with my 18-200.
The Nikkor 70-200 2.8 - according to many sources, it may be updated soon. And it sorely needs updating (to match the newer 14-24 and 24-70), especially it needs better coating (flare reduction) and perhaps the newer VR. Why pay a premium for an old lens when a new one may be around the corner? Why not wait a bit? And while waiting... yes, shoot the 18-200.
The 18-200 is a very versatile and great for travel lens, perfect for a dslr newbie, and perfect as a fill-in lens while figuring out what and when to buy next.