I lived in Saudi Arabia and Germany for a total of 9 years from 1981 until 1991. While in Arabia, my children were age 11 and 5 when we first arrived (we traveled a lot from Saudi Arabia). Later, I was in Germany with my Wife and step-children, starting ages 15 and 13. Europe was not as overrun with tourists as it is today. The line entering St. Marks in Venice was short as well as into the Sistine Chapel. When my Son was 5-6 years old, I wound up carrying him on my shoulders quite a bit, since he would get tired later in the day. We took the kids to all the places that people go when they visit Europe. Museums were a special task, since, I remember after about an hour at the Lourve, my Son, then 7 was ready to go. I will say this, at 7 he was still in awe of the Sistine Chapel and wanted me to explain to him all the details on the paintings. Still, I can say that today, he still doesn't remember a lot of the places we visited when he was 10 years old or younger. However, teens were different. Teens will absorb a lot of the history, architecture and culture. Be ready to explain it to them. I used Michelin guides in those days. I will say that it never hurts to plan to stop in places where the kids might have more of an interest. Going to see natural wonders like the Zugspitz Mountain top is an example, or the beach in France. A Seine river ride in Paris or going to the top of the Eiffel Tower was a winner. My Son, at 10 was awed by all the Egyptian tombs and temples, but really impressed by the Aswan Dam. All my kids (including step kids) love to travel and I think taking them on trips had something to do with that.