There are some things to keep in mind when looking at using the 6500s for WAN connectivity. Yes they will indeed work but by definition the 6500 is a switch line and the SUP720s VSS or regular do not always support the types of interfaces you may need to front end that WAN connectivity.
For instance, if you are looking at using Gig links from a provider and want to do things like outbound queueing, you will more than likely need to go down the line of using a SIP module with SPA cards. This is most definitely the way to go but a tad more expensive than using regular interfaces or the on-board interfaces of a supervisor module. Here is the fun part...those types of interfaces aren't always readily supported by SUP720 (especially the VSS variety) software. This is because Cisco drew a line in the sand a few years back and started decoupling the 6500 software from that of the 7600 (more router than switch) models. You'll find the 7600 series software tend to support a lot more.
There is something to be said about decoupling your WAN edge infrastructure to that of your DC or switching infrastructure. Trust me, we've been through this one a million times over. Anyhow, you could go either way but do your homework and take into account not only what you are planning to do today but you will do in the future (sometimes tough to envision).
Finally, for purely terminating those Gig links and being able to route at wire speed you should also at least consider the ASR line. Even the small ones (1002s) can handle what you want to do.
