I got the Tamron 18-200 - and it is cheap - - and all-around. But it covers more than 10 times of zoom and a lot of compromises. I never found it as good as my old kit-lens 18-55, which came (and went) with my D60. But it is of course more flexible.
I'm myself ready to buy the Sigma 17-70 (trying to get a used a Little cheaper) and this about 5 is the highest I want as zoom-factor.
I would better recommend two lenses, 18-55 and 55-200, both lenses cheap, than one covering the same range.