Originally Posted by
53flyer
Yes you can use SWU's if you are booked in Y, B or M class (same as for a miles upgrade). Any other fare class is not eligible for an INTERNATIONAL upgrade.
If you fly any long-haul domestic routes, you can also use SWUs on K+ fares for those. It's probably worth it on 4+ hour t-cons, especially the routes that offer true BE service or on repositioning flights with an international configuration.