How to sync compiled code to multiple EC2 instances

Elastic Beanstalk seems to be the best route to go now. You simply push your web deploy project to an elastic beanstalk environment and it deploys code to all of your instances. (It manages auto scaling for you.) It also makes sure that new instances launched will have you latest code and it keeps previous versions which you can easily roll back to.

If your asp.net website needs to be auto scaled on AWS, Elastic Beanstalk is really the best end-to-end solution.