There are three(3) suggestions I have that you may want to look into...
You could use MySQL 5.5 both locally and in AWS. You would also setup Semisync Replication. That way, every SQL statement executed on the Master has its latest recorded SQL statement sent over to the Slave.
In my past post (
Jul 26, 2012 : Mysql database replication on different vlan/subnet/another site) I had recommended SemiSynchronous Replication over a geographic distance. Interestingly, @AaronBrown points out by experimentation that High Latency would degrade Semisynch Replication (See his blog on this one).
If all your data is InnoDB, you could use Percona XtraDB Cluster (preferable to have two Slaves in AWS but one would do). Why Percona XtraDB Cluster? You have synchronized writes. You only major bottleneck would strictly be network communication (again High Latency would have an adverse affect)
Here are my past posts on using Percona XtraDB Cluster
If you want to strengthen each data center's local copy of the data, I would suggestion using DRBD, not over a geographic distance, but having a DRBD cluster in each data center. In your case, at least have DRBD in the local data center.
Here is my past post on this suggestion :