[M_Six]

We're taking a long-postponed trip to Germany, Czech Republic, and Austria in October. I'm thinking of moving up to a true DSLR from my Lumix DMC-FZ18. Thing is, I want to travel as light as possible. If you had one lens to bring with you on such a trip, what would it be? I'm not looking for specific brands or specs, just a focal length range. For instance, the Nikon D90 comes with an 18-105mm lens. Think that will suffice for most situations?