If ELB is down in a given region then DNS failover to another region. Assuming you feel comfortable rolling your entire infrastructure monthly, have good images

If ELB is down in a given region then DNS failover to another region. Assuming you feel comfortable rolling your entire infrastructure monthly, have good images / configuration management, and have the state replicated in the backup region. That or sidestep ELB in your region to a team of stateless load balancers that terminate SSL.