If I were to only take one lens I believe it would be the 18-200 simply based on range. I have a D7000 with Sigma 8-16, Sigma 17-70 and Nikkor 18-200. This past Spring we spent a month in Chicago and I found that carrying all my stuff wasn't practical so I pared down to just one, on camera, lens and it was the 18-200.
Also, I found with my Nikkor 18 -200 that it performs best at f/10. You might conduct your tests of various lenses at different apertures and see where each lens performs the best.