I personally wouldn't get a lens with too big a zoom range as they are inevitably a compromise in zoom range over quality imho.
I found the Nikon 18-70mm a cracking lens for the money, though I got it with both the D70 and the D200, it has proved to be a high quality kit lens. When mine got damaged I decided to replace it with the Nikon 16-85mm VR which I've found to be a great lens.
When I had the D70, I had the Sigma 70-300mm APO Macro and was quite happy with the lens, and the the price.

However when I upgraded to the D200 the Sigma suddenly didn't seem that good, being quite soft.

I think the jump from 6Mp to 10Mp showed up the quality of the Sigma. The D90 sensor is a generation beyond the D200, and an extra 2Mp, so may give similar results as I got with the Sigma. I replaced the Sigma with the Nikon 70-300mm VR (from Kerso I think) and that was an obvious a step up from the Sigma. I do miss the Macro setting on the Sigma though.
With the 16-85mm and the 70-300mm there is a nice overlap of zoom range between the 2.

The 16mm at the wide end is a surprisingly big difference compared to the 18mm 0f the 18-70mm too.