Personally, I would find the framerate on the D800 way to low for wildlife, so for me the D4 would be the choice for this type of photography. For landscapes on the other hand, the D800 would be ideal. I shoot both so I'll want both
This said, I still shoot with the D200 too, and that gives me only 5 fps, slower than the 6fps in DX crop of the D800 (with the right battery). So it goes to show you can get wildlife results even with slower framerates (but as said, I'd prefer the higher count).