My wife shoots a D7000 and I was looking for a lens that would upgrade her 18-55. She also has a 70-300 and a 55-200 (not used much these days). I read a few reviews about the 17-55 and most imply that it is not a significant improvement over the 18-55.. perhaps there is no reasonable cost-effective one. Short of moving to a 24-70, can anyone recommend a lens in a similar range to the 18-55 that might provide better IQ? The 18-55 is really not that bad, so this may be a futile search, but just curious about other options. Thanks much. D.