My work is in landscape photography, and I do not use (nor like) HDR---so digging shadows out is part of the normal work flow.
HDR doesn't automatically mean tonemapped surreal oversaturated poster art. HDR can be as simple as doing a two-shot bracket and using a graduated mask to composite the one onto the other, with results indistinguishable from what you'd get with a graduated neutral density filter.
If your horizon isn't a straight line, you can use a big, fat brush on the layer mask to create a virtual graduated ND filter that's a perfect match for the shape of the horizon -- think of it as having a high-end custom graduated ND filter fabrication shop right there on the spot.
And, from there, the sky's the limit. Do a three-shot bracket, one for the sky, one for the foreground, and one for the shadowed forest on the side of the mountain, and use that same broad brush to mask in each. (The 5DIII will automatically do those three shots for you at 6 FPS, and even give you a not-miserable preview on the LCD.) Use a harder brush for your architectural work, and so on. Just keep your shadows dark (with detail), your highlights bright (with detail), and make sure that no two parts in the middle come out with their tones reversed, and you've created a high-quality, natural-looking HDR photograph.
Oh -- and even the simplest of two-shot HDR landscapes processed like this, even if shot with a first-generation DSLR, with have dynamic range that blows away even medium format.
More dynamic range never hurts, but there are damned few scenarios where a 5DIII doesn't have enough dynamic range but the D800 does. Almost always, either you'll get far superior results with HDR on the 5DIII than a single exposure on the D800, or what you really need to do is fix the light. And the exceptions are generally fast-paced reportage (including sports and wildlife) where the D800's autofocus system and shooting speed might not be enough to get the shot in the first place....