small towns. Some options:
Italy: Rome (history/culture/art); hilltop towns in Umbria such as Assisi, Gubbio, Trevi (culture/history/scenery), Florence (culture/art/history). Rome and Florence are crowded but worth it.
Switzerland or Austria: Stay in a small town in the Alps and hike to a mountain "hut" (lodge). Some options are small towns in the mountains above Interlaken or small towns in the Grossglockner region of Austria.
France: Paris (art/culture/history); then a self-guided multi-day bike ride in the countryside. Many companies do all the arrangements and have lots of options and the bike paths are generally very good and the small towns are charming. One company is Le Velo Voyageur.
Aside from the iconic big cities like Paris and Rome, I'd skip the big cities. Big cities tend to look like big cities the world over. Most Americans are seeking the European look and feel that you'll find in the countryside and smaller towns.