> So the only feature of the database that needs backing up should be the data it holds - live replication servers that can act as background backup slaves are perfect for this.

Replication won't help if a "drop table users;" happens. You need point in time recovery.

You may want to backup log files and uploaded images/files.

The backups should be stored at your main service provider and also at a different unrelated place, so if AWS or whoever deletes your account, your backups aren't toast.

You also want an automated system for monitoring that your backups are happening and that you can restore from them.

If encrypting backups, don't forget to backup your encryption keys.