Suggestions for a first trip Europe with boys ages 11 and 8?

My family and I are thinking about going to Europe next year. We are a group of four, with two boys ages 11 and 8, who will be traveling from the East Coast of the U.S. None of us has been to Europe before, but we don't want to do more than three countries (AT MOST) on this trip. Do you have suggestions? I was considering the UK (England, Ireland, Scotland), OR France (possibly with Switzerland or Germany), OR Italy (possibly with Croatia or Austria). In other words, we have no idea! Any suggestions of destinations that are kid-friendly (without being theme parks) would be appreciated. Thanks.