Have you considered talking to an artist to create something for you? I do agree that the Coexist thing is a little played out but there's no reason you can't make it your own.
I've done a few tatoo designs. I do one the way they asked and one the way I would do it. The one thing that all the people have in common is they like my designs better than their ideas.
You're going to have this forever so spend a few extra dollars and have a pro give you something amazing.
Either way, good luck and I hope you enjoy it.
