I am trying to create a server with the lowest possible latency for my target audience. I get the difference between regions and Availability Zones (I think). It sounds like the Availability Zones are in different cities. Where are they exactly?
The best that Amazon provide in terms of public information is on their EC2 FAQ. If you want the lowest possible latency can you not just ping servers in each availability zone from your target location and find the lowest latency that way? There's no guarantee that physical proximity == lowest latency anyway.