Swiss (and Lufthansa) keep on promoting Istanbul as a destination the last couple of weeks. Swiss has a pretty good Economy class product.
A couple of dates in March have opened up for $573.
Note that the booking class will not (united Mileage Plus) or just 50% (Miles & Bonus) of miles.
** Only available after card approval. Minimum spend of $3,000 in the first 90 days required. Points redemption only available for purchase made with eligible travel merchants.