Swiss launched their late Spring fare sale with attractive pricing to most of their European destinations. By far the best deals are found for flights out of Boston or New York, where $480-$550 can get you to Paris and other ‘Western’ European cities. Fares to the rest of Europe from the East Coast range in the $550-$650 range.
From Chicago, expect to pay about $100 more than the East Coast fares to get to the same destinations. From the West Coast, you can get to Greece, Budapest and other cities for as low $720.
As usual, SWISS is fairly cryptic with the terms and conditions for the fares, and the website is not helpful as far as navigating multiple options without needing to reset the page each time to a certain departure city. What I was able to gather was that the fares are valid for travel between April 7 and June 5, with weekend surcharges if flying on Thursdays, Fridays, Saturdays, or Sundays.
As a reminder, SWISS is still running their Spring Business Class fare sale with prices starting at $2500 from the East Coast to most of Europe. You can find more details here.