One thing that complicates easy replication is the rules around CNAMEing your S3 bucket to a subdomain you control. You have to name the bucket subdomain.your-domain.com.s3.amazonaws.com, then CNAME subdomain to s3.amazonaws.com. Your replicated bucket needs a unique name, so when you want to fail over it's unfortunately not just a matter of changing a DNS entry to point to the alternate bucket.
Of course, if you have complete control of the client you can just change the hostname. But if you have references scattered throughout html files, you'll likely want a reverse proxy in front of S3.
Of course, if you have complete control of the client you can just change the hostname. But if you have references scattered throughout html files, you'll likely want a reverse proxy in front of S3.