[hackerspaces] Mesh network specs

[Todd]

I am looking to build a mesh network in chicago, The way we are planning 
to do it is, we have an uplink set up in a datacenter downtown with a 
100mbit connection, and a place for the antenna on the building that 
will go across the street to the 1st hop, which will then have several 
point to point links to the greater mesh network. So the plan is 
primarily to have many meshes, probably about 20, each with ~8 wireless 
routers, which are connected via point to point bridges. None of this is 
commercial, so we will not be worrying about things like zoning fr the 
antennas since they will all be on private properties. My question is, 
does this sound like a good plan, and if so, what specific hardware 
should be looking to use ?
  Please be specific as in technically specific (5ghz 16.5dbi yagi 
antenna) or list the manufacturer/link to hardware that is being suggested.