I structured my cabinet so that I have a pushbutton to turn the PC on/off, and another toggle switch which can turn the monitor, marquee, and coin door lights on/off. So I have a solution that works for me, as I can turn just the monitor off, but not the PC.
However, it's not me that I'm trying to find a solution for; it's for my kids. You can tell them that they need to turn off the monitor, if they've paused a game and need to leave for a while, but they always forget (they're kids after all). The cabinet has been left on with a game paused for several hours on a few occasions (for whatever reason), and that's probably not good for that old monitor.
Anyway that's my delemia, and I don't know if there's any good solution to that (short of disabling the pause button), but I thought I'd ask.