Originally Posted by
Kacee
1. Search using "expert mode" on united.com. "R" space is the upgrade fare class. If R>0 you can upgrade at booking. You should search segment by segment for the most accurate results. R may be available on some segments, but not others. If so, it will clear on those that are open and waitlist on those that are not.
2. I'm not sure why you're referring to W fare class. There is no requirement you book a W fare for a miles + co-pay upgrade. That is only a requirement for using a GPU on an international flight.
+1 even deep discount G, N, and similar fares can be upgraded ... just requires more $$$ then a B fare, for example.