The inability to turn the PA off while I'm sleeping has me seriously reconsidering using Amtrak for LD trips. I am not even joking.
On the old Superliners, our SCA would tell us to leave it on channel 2 or 3 or whatever to hear the PA and then switch it when we wanted silence. Why couldn't they make (for example) channel 2 be the dining car, cafe car, station stop, SCA "hey, check out the scenery" channel and channel 3 the emergency channel? That way, at night, I could switch over to channel 3 so we didn't miss something emergent.
Or, as another poster mentioned, have some kind of override.
I know I can't be the only person who hates being awakened at 6:30 AM. When you factor time zones into consideration, I really feel for all of the people coming from the west.