I am sorry your D800 disappoints you. I am delighted with my D800E. There are things I would change if Nikon let me re-design it! However as of now it is my choice over my D3X on every occasion and over my D3S except when high ISO and AF are needed.
I used Nikon film cameras for 25 years mainly with Kodachrome 25 ASA. I rarely thought of a camera except on a tripod. There were no AF lenses and no ‘good’ zooms. Being slow to change I still rarely use AF, even when available, and zoom lenses I use only on the D3S. VR is inappropriate for my photography. I have always purchased the highest quality lenses I can find. This has proved very sound because as cameras get better I can justify up-grading the low-cost part of my equipment, and I then get even more out of my lens investment.
Bearing the above in mind the D800E is a big step up. But it is different from the D3X. Best results are now at f 5.6 or less, whereas on the D3X I used f 8 as a routine. On a D2X I used f 8 and f 11, and on film f 11 and f 16. I have my notebooks going back 40 years showing this. As the resolution of in focus areas increases, out of focus areas are more noticeable. Then as wider apertures are used to avoid diffraction the depth of DOF, or more correctly depth of acceptable non-blur, gets less. This challenges many lenses and they fail to meet expectations. The failures are generally those with marked field curvature and/or focus shift. It is surprising how many commonly highly regarded lenses have so much curvature and focus shift that when focussed wide open (as is always the case in AF and in VF focussing) the point on which focus was determined is not in the plane of critical focus when the lens stops down in taking the photograph. In LV the lens is stopped down for focussing so what you see is much more likely to be what you get.
As others have said the 36 MP cameras test our technique. I have a rule of thumb now to use one over eight times the focal length as the exposure time for hand held shots, and to let the ISO rise to compensate. On a tripod for close-up work I use LV and remote release. To test AF on a tripod I use MUP, a 10 sec delay, and a remote release. For field use some of these techniques are inappropriate and have to be abandoned, but there is an inevitable loss of potential quality. I don’t normally use AF because I want to choose the focus point and not let the camera average various points, or for it to choose a single indeterminate point in the point focus setting: By the way the focus point symbol in the view finder is generally not where the camera is focussing, and though you can determine later where it did focus, by then it is too late! Another reason I don’t use AF is that my best lenses are all MF!
Perhaps before you explode your D800 you should determine whether you have lenses, or merely future paper-weights. Take something like a Lens Align device and check your lenses for focus shift, if they show shift, do an AF Fine tune until they focus in the plane of the target at the aperture you want to use. Then take a resolution chart and check the lens performance. For reference use either a Zeiss 50 mm f 2 Macro lens, or a Zeiss 100 mm f 2 Macro lens at f 4 or 5.6. My examples do not show focus shift and are flat-field. But take nothing on trust not even all Zeiss lenses are perfect or opinions valid. I am a scientist: Test data is gold dust, everything else is fluff.
I do hope you come to appreciate the D800. It has its flaws, but it is a beauty.