We will be traveling to Switzerland next September and have six days before beginning a river cruise in Basel. We can fly in most international airports. We love small cities and villages. We do not hike but can handle stairs and towns with steep roads. We want to travel by train. Any ideas would be helpful.
From North America, Zurich Airport is the best, since they have direct flights from a lot of cities, and usually the best prices. You can get anywhere in Switzerland from there. Luzern is just an hour on the train from the airport. From there, suggest Muerren or Wengen in the Berner Oberland. Lots to do and see and trains go everywhere, even places cars can't go. Between those two, easy to eat up 6 days. Then easy train connections to Basel.
Fly into Zurich; from Zurich Airport take the train to Luzern; stay in Luzern 2 nights including an excursion to Mt Pilatus weather permitting; then take the train from Luzern to Lauterbrunnen either stay in Lauterbrunnen valley or in one of the mountain villages for 3 nights include one mountain excursion to the Schilthorn for example. From Lauterbrunnen take the train to Basel