At the risk of turning this thread into something completely unrelated to the Tokina 12-24 (which I have tested, and am quite impressed with it's wide angle capabilities)...
Personally, I like to go wide in my shooting. A recent example was when I was in Cologne, and had to walk really far out to get in all of the magnificent Cologne Dom (old Gothic Cathedral). A 12-24 would have been sweet to capture that 157m high church. There were many shots that the 18mm wide-end of the kit lens simply could not deliver on.
Now, for the 50mm. I like the idea of shooting indoors without flash. The extra 2/3 of a stop that the 1.4 offers could prove useful. But Ken Rockwell seems to be of the opinion that the 50mm 1.4 Nikkor suffered a drop in quality (especially build quality) when they moved production from Japan to China. He seems to think that its unethical to sell full price products when you drop the quality - and he does have a point, I think!
18-200. My girlfriend seems to like the tele-end of lenses, so it looks like a good compromise lens top get. That, and the fact that she has trouble hand-holding even in bright sunlight means that the VR would be mighty handy. But I think it's a little too early to get that as its such a new lens, and the demand is over the top at the moment for it. Call me paranoid, but I believe that when you ramp up production to meet excessive demand, there must be some compromise on QC. So, better to wait until the euphoria dies down...
So, all things considered, I think TMC is right in suggesting that the 50mm 1.8 is a good starting point. Maybe I'll get it when I come back from my next trip.
Thanks for the tips! Much appreciated!