I just got a great deal on Swiss.com for nonstop flights Chicago to Vienna (Austrian airline) returning Zurich to Chicago (Swiss Air).
Both airlines are part of the Lufthansa group so I was able to book both routes on Swiss on the same ticket.
$794 total (not including what I paid for seat reservations). Trip is for Sept. I hadn’t planned on booking this early, but I don’t expect the price to get any cheaper than that. I've been checking and the price has always been over $1000. I don't remember exactly, but I believe it's been around $1200.
Not all routes appear to be on sale though. I already have RT Chicago to Zurich booked for June and I rechecked that price and it’s still over $1000.
Prices are for economy plus (cheap seats + 1 checked bag).