I have had a play with the 70-200VR and loved it, butdidn't have long with it.
We bought the 18-200 VR for my wife and the D70.
She loves it. Mainly because she's not into changing lenses, but I'm working on it.
Here's a post I made some time ago, a photo with the 18-200, summing up what I think of it. Note the crop of the moon just under the main pic.
In my opinion -
It's fine for everyday pics. It's portable and versatile.
It does not compare with the 70-200VR in regard to quality.
Why consider these two lenses as an either-or option? They are in different classes.
If you can afford the 70-200, don't mind the weight, don't need the versatility or don't mind carrying a wider lens as well, and/or want the extra quality, go the 70-200 or as has been said, the 80-200 and save a bit of coin.
But as you are considering these 2 lenses you are probably looking for VR.
F stop in the 70-200VR or the 80-200 is 2.8, where the 18-200VR is 3.5 to 5.6 I think.
I cannot comment on the 24-120VR but others have, I have read about it elsewhere and would not consider it myself, again it depends on what you are looking for, what your budget is, what weight you want to carry etc etc...
Isn't it fun deciding on a lens?
Our next lens purchase? Either the 85 f1.4 or the 17-55 f2.8, or 70-200VR, or .... Hhmmm