Manage Multiple Depths

Hey Boys and Girls.
So I’ve created an interactive map that loads info in from a csv file and displays that information on 120 cities with a radius around each city.
The cities have been manually placed on the map and the data is sent to them from a custom function.
The problem I’m having is with the RollOver effect on the radius as some of my cities end up underneath the other ones as the radius grow and subtract through a timeline.
I’m just wondering of the best way to give each city a set depth and then arrange the depth order within a set number of depths.
Should I attempt to put all the cities in an array that way I can check the size of each city in the array and order the depth = to the value of the radius size.
I’ve been searching forums and google for a bit on this one.
Anyone have any suggestions or examples?