Comments that you occasionally read about the D3 not being a landscape camera are just plain silly. It works exceptionally well in that capacity. If you haven't used a D3, it's hard to appreciate some of the rule-breaking aspects of its sensor. First, because it has such a low noise level, you can apply slightly different capture sharpening to bring out fine detail (higher intensity, lower radius, lower threshold) without creating a problem in the shadows. Second, as already mentioned by Jason, low ISO with this sensor is ISO 1000 and below. It's hard to get used to the idea of shooting landscapes or macro shots at ISO 1000, but you get beautifully clear and colorful images at that ISO. That can help a lot with moving subjects, especially if you're also using polarizers and/or grad filters. I think most landscape photographers benefit more from having increased options at the wide end rather than the long end, and lenses like 14-24mm certainly expand the range of options that are available. Ditto with the extremely nice 24mm 3.5 PC-E and 85mm PC-E, both of which I greatly prefer using on an FX body.
In addition to the above items that are more landscape oriented, don't ignore the benefits of the D3/D700 sensor for general photography. For everything except some types of wildlife photography (birds and small mammals), the sensor is great. It's liberating being able to shoot available light at ISO 3200 with excellent color and detail. After having used the D3 and D300 since they were introduced, I find myself using the D3 90% of the time, with the D300 getting used primarily because of its smaller size, and not so much because of the format. Those figures are based on my shooting preferences, so yours are likely to be different, but if I end up with a D700, the percentage of shots made on DX bodies is likely to plummet.