What Lens for Luggability?

You did not tell us whether you plan to shoot stills, video or both. If you plan to take any video you should consider taking a lens that is optimised for video shooting. On my vacation last summer in Croatia 90% of my still images and 100% of my video sequences were shot on a Panasonic GH2 with the video-optimised 14-140mm lens. If I was starting from scratch I would of course consider the newer 12-35mm alternative, but Iam not starting from scratch, and the 14-140 was the 'kit' lens with the GH2.

In late November 2013 there will be fewer hours of daylight than in the height of summer, so taking a faster lens such as the 12-35mm constant f2.8 is also a consideration.

Speaking as a European who has lived and worked in the US, one of the things that will take you some time to get used to is that Europe is a much more crowded/concentrated continent than North America, so scope for 'zooming with your feet' with a prime lens can be limited. For landscape and architectural photography you will often need a wide angle of view if you are going to capture all you want to include in the scene. Again the 12-35mm has advantages here as a single lens solution.

My ideal European vacation travel kit is a trio of lenses in a small backpack, 14-140mm, 7-14mm and 20mm f1.7, all supplemented by the still amazing, and large pocketable, Panasonic LX3. If size really matters and you never plan to print larger than 8" x 10", then consider a quality compact such as the LX3/5/7 or the Olympus XZ1/2 or even a bridge camera such as the Panasonic FZ200.