If you're gonna be shooting 21MP, get the glass that makes it worth it. I can see a clear resolution difference between my 50mm 1.8 (dxo rates it top 3 or 5 of nikons most highres lenses, not incl old ones) and my normal zoom lens (that is still supersharp). And that's 12mp.
Think like this: if both were 12, what would you get? Only people that does fashion needs that many pixels (and it's only the editing that needs them, the billboards aren't even that high res).
Just skimmed this page, so sorry if it has nothing to do with the resolution. Talking as a D700 user though, I've started to get dependent on all the quick switches on my D700, after using it these 3 months. Going from 51point Af, two switches (one point Af and continuous Af) and I have focus tracking on the subject I choose. I've also set the regular "choose a point Af" to 11 points, which makes it fast for me to move the point across the viewfinder since you usually do not have to be spot on, just move one degree and Af, hold and take photo.
The most useful thing that I would have a hard time without, only after three months with it, is that I set the middle button on the multiselector to 100% zoom on the image - one second to check the sharpness. It zooms 100% on the focuspoint you used in the photo.