Lens Suggestion for City Scapes

Hi All:

Another lens question here. I have a Canon 60D with an EF-S 18-200 lens. I just found out we will be spending a couple of weeks in Europe this winter, giving me the opportunity to spend some serious time photographing various city scapes.

Any recommendations on a good lens for this. While I like my 18-200, I would like a faster lens. On a somewhat related topic in a previous posting, someone suggested I look at Canon's 15-85 lens. This lens has a f/3.5-5.6 and I worry about it being too slow.

Since I do not do any city scape work (most of my work is wildlife and landscape), can anyone provide me some guidance w.r.t a better lens than my 18-200?

Thanks,
Harold