Put some cash in the fire safe. If someone breaks into it (thinking there is money) they will probably be less likely to take other things in the safe or destroy those items (I mean a hard drive they might leave - obviously they will take anything of clear value). Assumption also is that the HD is encrypted.
This comes via a practice a long time ago with cash registers. You leave the cash register unlocked and put some cash in it. Thief is presumably happy and doesn't trash the rest of the place.
"Any passwords and serial numbers and etc are printed out, with the name and URL of the software they're for. A copy of that goes in the fire safe. "
Doesn't seem like a good idea to put plain text passwords (is that what you are saying) in a place that someone will look thinking there is something else of value in there.
The typical fire safe is meant to prevent auto-ignition of paper. That means that your media could easily be subjected to temps up to 400 F -- maybe higher!
You've controlled for this by sending them offsite as well, but most ppl won't!
That stuff gets archived (zero compression) with recovery data; with PAR2 recovery data as well; it then gets copied to multiple USB sticks and microSD cards. These get posted out to various family members (who are asked nicely to keep them somewhere safe) and kept in my firesafe.
Any passwords and serial numbers and etc are printed out, with the name and URL of the software they're for. A copy of that goes in the fire safe. There are copies of the spreadsheet on various drives.
All the other stuff is kruft. I do have multiple copies of my music but that's only because tagging MP3 files is hell.
I'd be interested to hear how the drobo failed.