Nogbad,
Zoom lenses aside for a moment. I read you do some macro work....
If you want the ultimate in macro quality there is really only one lens to consider..... Nikons very own 105mm f/2.8 AF-S VR glass.
A small business specialising in watches and jewelry bought one from us not too long ago, wanting the sharpest clearest pics, we tried them all, the quality from that lenses blew all competition away! (inc similar optics from Canon and Zeiss)
Forget Sigma, Tamron or even the debate of Nikon vs Canon...there is simply no competition....
If you want REALLY amazing macro shots this is the lens to go for....
Take your zoom lenses off you thought were good and try one to see the difference
....and you'll thank me for it when you ditch the 60mm! lol
Failing this, a 400mm seems the logical next step, as Don suggests.
A f/5.6 version if buying new, or maybe an f/4 if buying s/h (and don't mind manual focus)
Good luck and happy hunting for gear...wishing I was there!