I've got the original 18-55 kit lens and the non-VR 55-200. Both can produce excellent images, and are really sharp when slightly stopped down. The 18-55 can make a flat horizon appear slightly curved at 18mm, but that's a common thing at 18mm for most similar lenses. The 200 can produce some remarkably sharp and contrasty images. Stopped down just a bit, it's excellent. But it's not a fast lens, either in light requirements, or in focusing action. Not really a good sports lens. If it had more reach, I might use it more.
But... I find I hardly use the 55-200. I agree that the 55mm focal length just requires too many lens changes if working in the range of the two lenses, and I find that I now just work within the range of one of the lenses for the most part. I think the 18-70 and a 70-200 would be much more ideal.
I'd say the 18-200 might just get used more in the middle ranges, and be more readily available for shots you'd miss otherwise - just more flexible in street shooting. Image quality should be very similar under most normal conditions of hand-held shooting. Technique will have more of a bearing on your image quality than the lens, so look at the convenience factor.