My thought: Have a very nice screen for your mobile app/website that says "We are down for maintenance, please stand by." Sorry to be fatalist, but it's a hard

My thought: Have a very nice screen for your mobile app/website that says "We are down for maintenance, please stand by." Sorry to be fatalist, but it's a hard problem. This last outage was more than just an AZ failure. Region-wide API usage was affected, so operations like static IP reassignment and ELB changes were not taking effect. This means you are hanging out in the wind should there be something unusual that requires manual intervention (as was the case with us). Route 53 is a good service but I don't know how its control plane works, and it could be that problems in a single region would disable the ability to update DNS records (I would guess that DNS reads are a lot more available than writes). And in any case DNS is not a very good failover mechanism due to upstream caching. Unless your business model requires higher reliability than Instagram, Netflix, and Pinterest, I'd suggest going multi-AZ, crossing your fingers, and doing everything else right.