Great post!
The symbols for the numbers 6 and 7 had meaning in the Semitic root language that Hebrew came from. The "6" meant incomplete and the "7" meant complete. So it may be that the reason 666 is chosen as the mark of the beast is because his followers follow the incomplete one, while Jesus' followers follow the complete One.
To be honest, whether or not that's true is an intellectual exercise. But what about practical application in our daily lives? I say treat the mark of the beast and the mark of Christ in Revelation as symbols of your creed and what you identify as and stand for. It's possible that Revelation puts those marks on the forehead and hand to symbolically represent what people always remember, like Moses wrote in Exodus 13:9 (perhaps a colloquial expression of the Jews when he said "This observance will be for you like a sign on your hand and a reminder on your forehead that this law of the Lord is to be on your lips. For the Lord brought you out of Egypt with his mighty hand." So it's possible that we're not talking about a situation of everybody having some kind of physical mark. It's possible we're talking about some kind of culture or government that requires people to bow to some religion or belief or creed in order to be able to buy and sell, while Christ is watching for people who choose to believe in Him enough to stick to Him like glue with a no-matter-what, no-matter-who kind of attitude.
Even if I'm wrong, even if there will one day come some literal marks of beast and marks of Christ, between now and then we should probably operate like the Revelation teaching is about which creed we stick to. Stick to the creed of the complete Jesus, not the incomplete world. Even if the world makes it hurt. In the end Jesus wins.