Wants are great, but you know what they say about them, right? Want in one hand, shit in the other.
Most important thing is budget, followed closely by location.
How many sites? What are the topology needs? How many users at each site? Do you have any sites in carrier hotels or other colo facilities?
If your budget isn't $100k for equipment alone, you can forget about 10gige. The costs for routers and firewalls that can operate at those speeds are pretty outrageous.
Basically, need more info.
Specifically, SONET can operate at 10+ gbps. In fact, early 10Gig-E implementations were based on OC192 specs, which was essentially four 2.5gbps channels (OC48 operates at ~2.5gbps.) And 40 Gig-E is based largely on OC768 specs.
MPLS is not a connection type. It's a protocol that's used to facilitate the routing of packets independent of their L3 addresses. As such, MPLS is typically used to build VPNs across a service provider's shared resources. The cost savings in not having to build circuits end-to-end are huge. It's also used within a SP network to enable faster, potentially more efficient, routing.
10 GigE WAN connections are not common outside of colocation facilities. Even then, you'll pay out the ass for them. The cheaper ones (Hurricane Electric, etc) are probably still on the order of $10k/mo for Internet access. Private line/virtual private line will be significantly more expensive than that. As an organization, you'll never get neutral peering.
Judging by your questions, it's unlikely that you need or can afford those kinds of speeds.
