Well, I decided on one of these. Smaller and more durable than the cheapish military dog tag I was considering. Simple. My first name on one side, mobile on the other. 3/4" in diameter.
No, I'm not affiliated with this ebayer, just trying to help in case anyone is interested.
http://www.ebay.com/itm/201454808496...%3AMEBIDX%3AIT