Backup is something of a holy grail for me. There is so much that needs a backup strategy, and no single tool that does it all..
Photos, videos, laptops, servers. All from various devices spread over the house. I'm using this post to document my current strategy, the choices I made and the difficulties I have yet to overcome.
Photos come from a variety of devices (a few phones, two DSLRs, a pocket camera). I use a manual workflow to copy all photos to a mirrored zpool on my NAS. The folder structure simply is year-month-day, with a short description in the folder name. Shoebox is my offsite backup of choice. It simply works, has great customer support and I love the "this day in history" (daily) digest mail you receive that allow you to rediscover your photos. Until recently I also used Crashplan to backup the photos offsite, but have now switched to Stack.
I use the same manual workflow to store videos on the NAS. Shoebox does not backup videos from the Mac app, only from the iOS version. This is one of the reasons I am using Stack to do another offsite backup of all photos including video.
We have several workstations in the house, all Macs. With yarg - which basically is an rsync gui, the user folders are transferred daily to a raidz-2 zpool on my NAS. Until recently Crashplan was used to back these up offsite, but now I am not so sure (see "A word on Crashplan" below).
Even though Macs can be backed up with a set of tools including both hardware (TimeMachine) and software (CarbonCopyCloner, SuperDuper), I am not using any of those. I am relying on OSX builtin recovery. It's probably not the smartest thing to do, but in the 20+ years I have been using Macs I've never had the need to rescue boot them, or have bootable copies of the startup drive at hand.
The NAS is not backed up. This is simply not possible in a cost effective way - I would need another 54Tb somewhere, or use tape backup (LTO5 or higher).
The SmartOS machine is - sadly - not backed up either. I am relying on the mirrored pool for now. Backing up would mean stopping the zones and VMs, snapshotting and sending that snapshot to some other place, such as detailed by Russell Ballestrini. Somehow though, I think that is too complicated. Maybe I should use FiFo's backup mechanism. But there has to be a better way to backup SmartOS zones in a non intrusive way.
A quite big dilemma is whether I backup an entire zone, backup everything in the zone, or both. An example: I run a Percona database in a zone. Do I backup the zone, or do I backup the database? I am backing up the database every now and then, but there is no real schedule behind that. The reason for this is that there are so many applications (elasticsearch, logstash, rabbitmq, redis, percona, node, nginx to name just a few) that need their content backed up, that it is pretty much impossible - especially for the homelab enthusiast - to implement it all. This is one of my most important challenges: administering the rack in my garage simply takes too much time. Sometimes I dream of an application (maybe a bit like Juju?) where I just select the applications I have, their location over ssh, and have the application do its backup magic.
Of a previous NAS, I still keep the drives. I have a Codegen chassis containing 6x1Tb drives, which I intend to use as a backup server. This will at least allow me to use the NAS as a NAS instead of a backup device.
A word on Crashplan
I have been a Crashplan customer since 2010 and have a family plan. It is the only offsite backup service that offers multiple platform support (even Solaris, originally), allows for external drive backup and is priced decently. This being said, I do have a love-hate relationship with it. It has been completely unreliable off late and their support is non-existent. Issues I have with it include freezing during a scan, incredibly slow upload speeds and a randomly crashing Crashplan agent, to name just a few. When it just deleted my complete Macbook backup archive (built up over 6 years), I was done with it. Your mileage may vary - I was a happy user until I started to get these issues. Sad to see you go Crashplan.
 Arq just introduced a new version of their backup software where they switch from per computer to per user licensing. Maybe combining that with Amazon Unlimited Everything offers a decent replacement for Crashplan...
[edit 21-5-2016] After Crashplan support took well over a month to inform me that 700 gig of backupdata amassed over a period of 5-6 years containing about a million files were lost because I made a mistake (and they have a logfile to show that I made that mistake) I gave up on them. It is not a mistake I would make, but it is small individual against large corporation. Not worth it. So I have switched to a combination of Arq Backup and Amazon Cloud Everything. It's a bit cheaper than Crashplan Family actually, but a price cut is not necessarily what I was after.