I was in Vegas when my 18-200 stopped working, so I started using my 50 1.8 AF D. It was great shooting a fast lens. The photos were sharp with excellent contrast. The only inconvenience was that the 50 mm wasn't wide enough.
I tried a Sigma 15-30 but found the lens cumbersome and the images too soft for my liking. My preference is to purchase a wide prime that is light for travel, fast & sharp like the 50mm.