We are running on aws where we run everything in 1 region and use AZ's for our services. So if a AZ failed we would still be "up" and servicing our customers.
From reading the Reliability Pillar of the AWS Well-Architected documentation, this would suggest that this is enough to do in the case of a failure:
Unless you require a multi-region strategy, we advise you to meet your recovery objectives in AWS using multiple Availability Zones within an AWS Region.
A see tools out there like Cloud Endure and Druva CloudRange, but they seem like more for on premise or other cloud providers migrating or recovering on aws.
My question is, it is hard to definitively find, but it appears regions never go down, maybe services within a AZ or the AZ goes down, so if you are using AZ's for your applications and databases and doing backups to s3(Cross-Region replication) is this enough for DR?