Case in point: The Heroku load-balancing issue is a nasty one. The random algorithm (the one they went with) leads to really nasty queues in some places, it's super inefficient. On the other hand, a greedy algorithm doesn't scale well. You get one Heroku dyno (or SimCity road) swamped by all the agents making the same decision.

A popular load-balancing strategy that finds a middle ground is "best-of-two" routing where you choose two servers at random and route to the one with lower load. There are probably similarly simple ways to introduce variety and randomness into the SimCity agents.