1. A system for calculating routes for a plurality of vehicles in a vehicle fleet, the system comprising: output interface circuitry configured to communicate with a fleet of vehicles; and processing circuitry comprising computer hardware configured to: identify one or more custom characteristics of one vehicle of a fleet of vehicles or of routes traveled by the one vehicle, the one or more custom characteristics comprising one or more of a vehicle type, a route optimization preference, and an avoidable road condition; calculate a plurality of simulated routes for the one vehicle on a network of streets in a geographic region between a plurality of selected waypoint locations using the one or more custom characteristics to influence determination of the plurality of simulated routes, the plurality of simulated routes comprising trial routes across the network indicative of preferred paths of travel by the one vehicle in the network and not actual paths to be traveled by the one vehicle in the network; based at least on the plurality of simulated routes, assign one of a plurality of classifications to individual streets of the network according to an estimated importance of the individual streets of the network to routes of different lengths; store the assigned classifications in a computer database; subsequent to the storage of the assigned classifications, identify a starting waypoint location and an ending waypoint location for an actual route to be traveled by a fleet vehicle of the fleet of vehicles, an attribute of the fleet vehicle or of routes traveled by the fleet vehicle matching at least one of the one or more custom characteristics; access the assigned classifications from the computer database; calculate the actual route on the network between the starting waypoint location and the ending waypoint location using the assigned classifications to exclude at least some of the individual streets of the network from evaluation for inclusion in the actual route; and output, via the output interface circuitry, data representing the actual route for presentation to a driver of the fleet vehicle.