If money's no object then I'm sure most people would recommend the nikon 24-70mm. If money is limited then the 16-85 lens you have already, provided it's not a DX lens, seems perfectly functional.
I use a Tamron 28-75mm f/2.8
Tamron 28-75 would be my first port of call - super IQ, and small, light and very sharp.
If you can find one, I reckon a Tamron 24-135 is excellent too - excellent range, super colours, sharpness and constrast.
Nikkor 28-105 f/3.5 - f/4.5 AF-D is also excellent.
There is the Nikkor 24-70 off course, super optics, but IMHO too big for casual walkabouts. Ditto the 28-70 f/2.8 AF-S.
Nikkor 24-120 VR is reasonable, but unless you get very lucky, these are optical dogs.
Another nod towards the Tamron 28-75mm f/2.8.![]()
Another vote here and I have sbd123's one here![]()
I use a Tamron 28-75mm f/2.8
This is strange, isn't it? If the OP were thinking of buying a full-frame Canon (eg a 5d Mk II), it would be very easy indeed to recommend the EF 24-105mm f/4 L IS as the ideal walkabout lens. But Nikon apparently don't make an ideal walkabout lens for their flagship DSLRs.....
Another nod towards the Tamron 28-75mm f/2.8.![]()
It would also be remiss of me not to mention that if you want a lens for "walkabout" (which I take to mean casual snapshots), you could buy a D40 + kit lens, for less than the price of some of the lenses options mentioned here. It might even be lighter too.
?I have the 24-120 included in the d700 bundle from jessops £1999.
seems ok to me, but dont have anything to compare it with (yet)
how do I know whether its a 'dog' or not?