Thanks for jumping in, PacketTracer. We've got someone who knows this stuff now.
So, the 6rd doesn't even use a separate WAN IP address. Gotcha. Makes sense now. I was thinking it would need one, and the ISP would route all LAN side packets to that, letting the router forward it to the LAN side. But I can see how you could set it up not to need one really, since it's a tunnel and the IP4 network gets it to the router's WAN IP4 address.
I'll read over the rest of your reply and try. If you didn't catch the last message, I did get a working IPv6 setup via a TunnelBroker tunnel, which worked like a charm.
Charter's 6rd Border Relay info is here on this page:
http://www.myaccount.charter.com/customers/Support.aspx?SupportArticleID=2665
Scroll down to the "Preparing for IPv6" section. That's the information I entered in, and checked it. When I enable it, I can't ping anything, including the default gateway, which is listed as ::IP4Border, where IP4Border is the IP4 address of the border relay. Since I got the Tunnel Broker tunnel working, I'll be playing with that for a bit, and I'll get some screeen shots of the 6rd status later tonight.