Originally Posted by
UACPAFlier
They say that you can get a free schedule change but must be in the same ticketing class. Tried to change online to a later flight than a 6AM departure and it says to pay $1500 more (U class).
Fare class goes out the window on a schedule change. As others have already said, pick the flights you want (and if it you get any pushback, thank the agent, hang up, and call again). UA has three daily nonstops PHX-SFO so I'd definitely ditch the DEN connection.