This mom is an expert travel. Here are the charming small towns she thinks you should add to your travel itinerary. Credit: Getty ImagesOn a recent big-city trip packed with museums, sightseeing, and nonstop walking, I looked over at my exhausted husband and sticky-faced kids, ages 3, 8, and 13, and thought: this is too much. I’d wanted to see this city for a long time, but if I were honest with myself, the truth is that some of our best family …