I use my iPad as my primary computer; I create and edit documents, manage photos, take notes, and otherwise fill it with important data. I rely on it backing itself up to iCloud, but also the photos, notes, and so on will sync to my Macs. Similarly for my iPhone; it backs up to the cloud, but the important data that I originate on the phone syncs to my other devices.
My main Mac Mini (called Haloumi) has a Drobo attached which I use for data storage, offering single-drive redundancy. Most of my documents are stored in a folder that is synchronised with Dropbox, so the content is available from all of my devices. The Drobo also contains my master store of photos (managed by Aperture), and media (managed by iTunes).
All of this content is backed up to an Apple Time Capsule in another room. The Drobo is also rsynced nightly to a local USB hard drive, and does a daily ZFS snapshot, retaining the last ninety snapshots. I also rsync my photos to a Strongspace account.
I log into the second Mac Mini (called Stilton) once a week or so, and make sure that it has synced down a copy of my Dropbox, so I always have a recent working copy should I need it.
And I still worry about my data being recoverable.
During the next year I have a plan to move to a RAIDZ2 instead of the Drobo, and to make backups of my data to similarly-specced storage along at qidane’s house by replicating incremental ZFS snapshots — it will be a lot more efficient than using rsync. We ought to be making more use of our wireless link down the street.