In my company we are using a mysql cluster based on galera, (percona xtradb server) and it's a master-master solution that is rather easy to deploy and maintain. The only limit was that we had to use a single server for writes (that would make the "cluster" thing kind of useless but it's not in fact, we are using a load balancer on top of the cluster and the load balancer decides of the "master" where writes go so it's transparent to our application), definitely worth a try.
Any info how "active-active-active" (I assume 3 aws regions) is accomplished?