Guidance on where to start and how to ensure we don’t overspend as we use the service.

I would start with the AWS pricing calculator which will help you plan and create cost estimates for using any AWS services, including AWS Workspaces. The following are some considerations you should take in this particular project:

1. Visit https://calculator.aws/#/ to create your initial estimate a. Not all regions support Workspaces b. Ensure to select a region close to your end users c. Check the Bundle Types (Standard, Power, Value, etc) to determine the required performance for your use case. Select the bundle that closely resembles your current utilization and estimate growth for the near future. I don’t recommend that you select the same exact configuration, but rather select something more powerful to support future applications. https://aws.amazon.com/workspaces/features/#Amazon_WorkSpaces_Bundles d. Since you are bringing more than 100 Workspaces to AWS, you may qualify to use your current Windows licenses to AWS providing your Microsoft agreement allows that.

2. Once the workspaces are deployed, you should implement Amazon Workspaces Cost Optimizer to automatically convert your Workspaces into the most cost-efficient billing option (hourly or monthly). This solution monitors your workspace utilization and optimizes cost by switching the Workspace running mode. Cost Optimizer, in combination with Cost allocation Tags will help you take a proactive approach to cost optimization and management to ensure that you don’t overpay for the service.
   https://docs.aws.amazon.com/workspaces/latest/adminguide/tag-workspaces-resources.html https://github.com/aws-solutions/cost-optimizer-for-amazon-workspaces https://solutions-reference.s3.amazonaws.com/cost-optimizer-for-amazon-workspaces/latest/cost-optimizer-for-amazon-workspaces.template (Cloud Formation template for Workspaces Cost Optimizer)

3. Once Cost Optimizer is launched, you can also proactively use CloudWatch to monitor your Workspaces to analyze performance metrics. The following article provides additional information on the metrics and dimensions that you can use with CloudWatch and AWS Workspaces. https://docs.aws.amazon.com/workspaces/latest/adminguide/cloudwatch-metrics.html

4. At the end of the month you can run reports from the AWS Workspace Cost Optimizer to determine if any of the workspaces requires termination. You can use AWS CloudFormation to provision and manage your entire Workspace fleet. When Cost Optimizer provides a recommendations, you can use CloudFormation to make the necessary changes. This will help you to continuously monitor and improve your service utilization, thus maintaining a proper cost control of your resources.

https://docs.aws.amazon.com/workspaces/latest/adminguide/launch-workspaces-tutorials.html

I hope this helps. Let me know if you need further clarification or additional details.