I didn't look this up, but my educated guess is that you have ear discomfort because the cabin pressure gets pretty low when the plane is up in the air, much lower than the pressure in your mid ear, thus pressuring your ear diaphragm to bulge outwards.
If that is true then wearing ear plugs, or sealing IEMs would help, because it eliminates the pressure difference. However once you take them off... which is something you can't really avoid... oh well.
The chewing gum/yawning method you've already mentioned actually gets to the root of the problem: releasing pressure from your mid ear.
I still think trying to sleep is the best thing to do. If my international flight is in the morning I usually won't sleep the previous night so I can just doze off naturally. Not sleeping in transpacific flights will usually give me extended jet lag, esp. flying west to Asia.