We have a SaaS application that we need to be highly available. We already have an expensive, well-maintained Hyper-V failover cluster, but today the datacenter where we host that cluster had a five-hour power outage that knocked us completely offline. So now we're wondering if a better approach might be to use servers at two separate datacenters. Assuming we get all the back-end file replication and data replication working between these two sites, we're wondering how to handle the front-end routing -- no wonder how we approach the problem, we always wind up with the load balancer being a single point of failure.
So the question is ... how can we set up load-balancing between two hosting sites such that the load balancer isn't the single point of failure? Is there a way to use two separate load balancers, one at each site? Should we be considering round-robin DNS?