Zoom Capability for Landscape Photography?

I have been an amateur photographer and am planning to take this up as a serious hobby though I can't devote my full attention to this fascinating hobby. The reason being I work full time and that leaves me with just the weekends to indulge in this hobby.

That said, I am particularly interested in low-light and night-time photography and am considering a switch to the DSLR world. I have mostly been a point-and-shoot kind of photographer and predominantly have used the Nikon Coolpix 5700 camera to shoot my pictures. I am looking at purchasing the Nikon D300 camera for a trip that I will be taking by the end of August.

One more question regarding lenses and their zoom capabilities: When shooting landscape pictures, what kind of zoom capability would you recommend? I have read a lot of articles about using the Nikkor 12-24 mm superwide angle lens for outdoor and nature photography, while a lot of professionals have also mentioned that they personally would prefer to use the Nikkor 18-200 mm lens that has become the darling of the masses (at least users of Nikon). I'm just curious to find out which one people here personally prefer.

I would think that the 12-24 would be ideal for landscape photography, giving the equivalent of 18-36mm on a 35mm camera. I personally prefer shots around 24-28 mm for landscapes (and at most 20mm), as I find 20 and below to be a bit too wide for regular use (unless extreme perspective exaggeration is warranted).

I must admit that I have not read a lot about the 18-200, but I would suspect the 12-24 would give a better focal range for landscape use, and that the 12-24 may provide better optical quality (or at least not be as large).

As far as using zooms in general for landscapes, it is usually the case that a zoom lens can never (theoretically) be as good as a prime or fixed focal length lens. Lately, however, both Canon and Nikon have come out with some pretty good wide angle zoom lenses, but have not updated their wide angle primes in quite some time. This means that you may actually get equal or better optical quality with a high-end zoom lens.

I think I just might go in for the 12-24mm Nikkor lens at least for the moment, as the 18-200mm with its huge fan following is so back ordered that I'll have to wait at least 3 months at a minimum before I can get my hands on one.

Along with the 18-70mm that comes with the D300 kit I should be covered to also photograph portraits (weddings, graduation ceremonies etc.).