We are planning a trip to Switzerland (Interlaken) then train to Italy. Which city offers the best flights and prices from the US? Zurich, Bern?
The two major international airports in Switzerland are Zurich and Geneva. As to what city has the best prices, you'll have to do your own research. There is no one answer as it depends on airline, city you're leaving from, capacity, demand, etc.
Zurich has the biggest international size airport in Switzerland.
Washington D.C. to Zurich with one transfer at Dublin costed about $300, for me that is :P
I'm not sure about Geneva, but one nice thing about Zurich Flughafen (airport) is that the train station is directly beneath the airport terminal. Just take the escalator or elevator down and off you go. Zip zip.