I just had a domestic R/T with a companion and didn't even try to figure the system out. United.com said upgrade requested for both, but then that disappeared at T-24, and then our names were not on the upgrade waitlist. Did not split itinerary due to bad past experiences as listed in this thread. Inbound reservation did not list us as upgrade eligible, and again no names on upgrade waitlist once checked in. At least we got to sit together in Y for the whole trip.