I work from home so it is pretty crucial to have everything in a high availability mode. Here is what I do:
OS/programs on 250gb SSD
2nd 250gb SSD with ghost of primary SSD updated weekly
Data, Movies, Pics, etc.. on 2 - 2TB 7200rpm drives in Raid 1
Netgear ReadyNas314 with 4 3TB drives are used for nightly back up of the raid drives along with items from the rest of the family. I have a spare drive that I rotate in and keep at another location. I look forward to the day my internet connection will allow me to use a cloud solution for this.
Media devices pull from the NAS rather than having a drive connected elsewhere
Overkill for most, but works for me.
I had a similar setup. What I did was purchase a large capacity HDD for my PC (I have an SSD for my OS and frequently used apps) and keep all my photos, videos and other things on my secondary HDD.
Then I purchased a subscription to Backblaze. It's $5 a month for unlimited backup and it's a nice peace of mind should anything happen to my hardware. Sure, I could get a new hard drive every year for that price (as cheap as it is) but it's super simple and does automatic backups once a week and all I have to worry about is putting new data on my drive and it's safe.