Looking for experience with keywording my images.

I usually know where all my images are stored and generally by date, and location. My folder structure is working perfectly and so far I've yet to fail in finding the image I'm after. But I'd like to make it easier on myself sometimes, and want to start using keywording in the XMP/IPTC fields in either ViewNX or Capture.. but I always seem to get stuck for a decent description other than:

<location>(easy for me as I'm a location based photogrpaher, and that's how I usually find my images)
<obvious subject matter>
<sometimes lens specific data> like a particular set of variables if I'm trying to work out where a lens works better or comparing lenses.

so here's a sample image...


Ok, no snide remarks about using two many Cokin GND's and pointing into the sun to create a blood red magenta hue in the sky

Some of the words I used for keywording were: melbourne, train, tracks, clouds, sunset, weather beyond that I get lost and block(photographers block). I can now see curve, bend, and maybe the letter 'S'

what else?

Oh, and I think I may try to use a program from the makers of BDSizer called idimager to do my searching and maybe any other useful cataloguing stuff that it may be able to do. From my minimal reading up on the software it sounds quite good, main basis for that observation is in their description of the way in which it works....
From the base up, IDimager is designed with an open cataloging architecture in mind. This means that you will be able to extract your information at any time, even without IDimager....
If there is a better program that costs way less(as in free) now would be a good time to share that information

I'm in no rush, I'm probably going to take at least a year to seek out and tag every image I have on my system. But I should get into a better routine of tagging the images as they get sorted in the download process. Batch inputting the metadata into the images is easy peasy using either of Nikons softwares,and it's directly into the NEF(which is my preference)

OK.. that's it.

... any input is muchly appreciated.