Originally Posted by jsloan

When does the GPU expire? Is it from 2016 flight activity (expiring January 2018) or 2017 activity (January 2019)? Do you have another use for the GPU before it expires?

Your question is really $310 + GPU or 30K miles, since the $600 cancels out. Unless you have another good use for the GPU, I'd say use it -- miles are much more flexible, and you don't have to worry about being stranded on the waitlist.

Edit: are you booked on the non-stop, UA79? I see J8 C8 D6 Z3 P1 PN0 R0 on 11/17, which is definitely a bad sign for your upgrade. And, yes, I do see J9 P9 PN6 R6 I3 on 11/15, but keep in mind that availability can change anytime, so if you decide to make the change, don't wait too long...