Rangatron,
I kind of have the same views on weathering as you do. When it comes down to painting and finishing a model, most of the time it seems I screw it up at some point. More weathering means more chance to mess up. So while I think some people can really pull off a great heavily weathered model--such as Karl, who posted above, and many others--I haven't quite gotten to the point where I'm willing to go as far.
In my limited knowledge and expertise I think there are a couple of caveats that are involved in answering your question straight up. I'd imagine those would include vehicle type, nation, time period, and the campaign location where the vehicle is serving as you depict it. While I cannot answer your question in terms of all of these caveats, I can try for a couple.
My favorite model that I've built would be this AAVP. I built it to be a stateside vehicle that was conducting training, thus I wanted mainly just some sand on it. I used some drybrushing, pastel "chalk" for the horizontal surfaces, and a very light airbrush spray for the vertical. The one that shows up the most is the latter.
I took an acrylic "sand" color (since this is an amphibious vehicle) and diluted it with water moreso than I usually would. Coupled with a lower pressure in the compressor, the coat was lighter and more subtle. I built up more coats at the bottom of the vehicle than the mid and top until it looked right, but so that it was still subtle enough to where you could see the details underneath.
There are many other techniques that you can use, however, I have not mastered them. You may get some great weathering ideas by searching the forums for builds of the vehicle you have in mind, and perusing the WIPs by different posters. A lot of WIPs have the techniques that are used, and some (again Karl comes to mind) post great tutorials on how they weather.