Today, we are introducing Amazon EC2 Spot placement score to help you find the optimal location for your Spot workloads. Spot Instances availability varies depending on the instance type, time of day, Region, and Availability Zone. Until now there was no way to find an optimal Region or Availability Zone to fulfill your Spot capacity needs without trying to launch Spot Instances there first. Now, Spot placement score can recommend a Region or Availability Zone based on your Spot capacity requirements. Spot placement score is useful for instance type flexible workloads that can be launched in any Region or Availability Zone.
Source:: Amazon AWS