It obviously may be easier to travel with another adult people – in such case, it is not that important if those adults are members of your family of friends. The most necessary thing is that these people would most presumably have similar interests and would like doing similar activities while on the trip with you. You might be sure that in any European city you would find something interesting to do for you and your companion. Nevertheless, the real challenge may be travelling with children. They most possibly will not be interested in visiting too many museum nor churches. You obviously need to select attractions for them more carefully. And this article might be helpful – it presents 2 European cities, which might be perfect to visit with your children.