How do SDCs work for saver first class tickets?

I may end up wasting 50,000 miles on a first class ticket this weekend, minimum 37.5k, and even doing that the flight options are pretty horrible (12 hour layovers, overnight layovers).

edit:

The most ultimate frustrating part in wasting 50,000 miles is that the flight I need to take could easily be accommodated by CX's YVR-JFK flight, meaning that same 50k miles could get me into CX Business Class, even if it is only a 6 hour flight, but nooooo of course things have to be broken between AS and CX. Worst part? There is availability for business class awards according to asiamiles.com