I recently had the opportunity to design a mesh WiFi network for a campus environment. I posted a more complete case-study over at Pulse Infomatics. This is just a brief overview but I think it covers the gist of the solution.
It utilizes Open Mesh access points and their Cloudtrax software for bandwidth monitoring and limits (when needed). Ubiquiti LiteBeam, NanoBeam, and Prism radios for high-speed backhauls to carry the client traffic. A Sonicwall router load-balances 3 broadband connections and provides Quality of Service (QOS) for VOIP traffic bound for an office network segment (not shown in the diagram).
The Ubiquiti backhauls can carry 450+ mb across distances of up to 15km (9+ miles). The Open Mesh devices and the CloudTrax software provides a way to visualize traffic utilization and provide basic and upgraded access to clients. Plus, we are notified if/when a device becomes unavailable.