I've been trying to decide between two lenses for my D7000, the Nikon 16-85 or the new release, now shipping, Sigma 17-70 2.8-4. Contemporary series. I find it difficult to use one prime for what I think of as WA on travel - including street, portrait and landscape. I'll probably carry a light normal prime for low light - indoors and at night. It'll be hard not to have my 70-300 along, but easy not to travel with and carry the 70-200.
I plan to keep my D7000 for awhile, but look at this lens as a step up from my 18-200 and a commitment to keeping a DX camera for what I like to do best, wildlife and birding.