How do you want to back data up? The 100 gig disks are insanely expensive, where you are better off buying external terabyte drives for the same price. However, the 25 gig BD-R disks are priced at a decent price/gigabyte ratio.
What I would do is one of three things:
1: Separate your data into 22 gig segments, then use Nero Burning ROM with its SecureDisk feature to burn the segments with some error correction. You can also add a cryptographic signature, as well as encryption if you want for each disk.
2: Make a massive, segmented WinRAR archive, perhaps with 2-3 recovery volumes to take into account for failed Blu-Ray disks. Then, burn each volume using #1 above.
3: Use a backup program. I used to swear by Retrospect, but their compatibility list is so narrow for drives, that the utility is all but worthless (if the drive is not on the list, Retrospect will not work with it, period.) One used to be able to manually configure a drive to work with it, but apparently that is gone now with the latest few versions.
The caveat about #3, although it is the easiest, is that you have to have the backup program and its serial number in the future. With #1 and #2, you can just copy the files off, or extract them. No utility needed.