It absolutely is easier to travel together with another adult people – in such case, it is not that important if these adults are members of your family of friends. The most relevant thing is that they would most probably have similar approach as yours and would enjoy doing similar things while on the trip with you. You might be sure that in every European city you would manage to find something nice to do for you and your friends. Nonetheless, the big challenge can be travelling with children. They most probably will not want to visit too many museum nor churches. You obviously have to pick up attractions for children more carefully. And this article might be helpful – it shows two European capitals, that might be perfect to visit with your child.