For most of your European images you would do fine with the 18-105 lens. However, we took a one-day cruise on the Rhine and shooting villages and castles from the boat we definitely needed more telephoto for many of those shots. We have the 18-200 precisely as a one-lens travel solution and we love it. I have not compared the reviews of the 18-200 with reviews of the 18-300, but I would recommend that you do so and select one of these as your lens for this trip. The longer focal lengths will serve you well for images from the boat (and maybe occasionally from land) while the short focal lengths will serve you well in the small, narrow lanes and interior shots. The VR feature will come in very handy when handholding the lens at long focal lengths, and at short focal lengths when indoors. (Locations like churches, cathedrals and others often forbid use of flash and you must use slow shutter speeds in the available light. ...and even if you can use flash, the spaces are sometimes so large that the flash cannot illuminate it anyway.) Note that at 200mm you will get about a 6x magnification over a "normal" lens for your D7000, so the image captured is like using a 6-power binocular. At 300mm you are getting about 9x magnification. To be quite honest with you, if I were buying today and the lens reviews for these two lenses are not too far apart, I would probably buy the 18-300 just for the extra flexibility. After all, you can always shoot the 18-300 at 200mm if the shot calls for it, but you can't zoom the 18-200 out to 300mm.
As with any equipment you want to use for a special trip like this, be sure you get your gear far enough ahead of time to practice and learn how to best use it before your trip. You will likely find that shooting at the middle range of apertures (say around f/8 to f/11) will give you the best images. In good outdoor light these apertures are easy. However, you should practice shooting indoors without flash to find out what is the best compromise between wider apertures and higher ISO settings to satisfy your personal needs for the images. (You probably won't want to shoot at f/11 and extremely high ISO indoors because of the increased noise at very high ISO settings, but each of us has different desires and expectations for our images so you need to find what will work best for you.)