The sign at the gate may toggle between Denver and San Francisco as destinations--can't remember if the gate signs behind the desks at ORD do this. The overhead signs jutting out into the corridor don't toggle between destinations, from what I recall, so that'll probably say Denver. The actual departure flight monitors, however, should list the flight 3 different times since it actually goes ORD-DEN-SFO-HNL:

UA 75 Denver 9:00 AM C11
UA 75 San Francisco 9:00 AM C11 1-stop
UA 75 Honolulu 9:00 AM C11 2-stop