I'm about 6 years ahead of you with the same problem. Lot's of pictures and video. Here is my current (and evolving) plan.
1. Everything is live on a NAS in my house. I don't do anything fancy like RAID. It's just a cheap harddrive. I do periodically swap out the hard-drive for a bigger one every few years and haven't had a failure yet...but that is just dumb luck.
2. I store everything in common formats, DVD images and jpeg. I figure that I'll notice if JPEGs or MPEG2 video becomes hard to decode and at that point I'll spend a weekend converting to something more "current".
3. Everything is backed up to a USB hard-drive that I keep in a fireproof media safe that is certified for media (hd, optical etc.). A standard safe won't stay cool enough.
4. Offsite backup using Crashplan. I like Crashplan but Mozy or Carbonite may work as well.
The USB HD in the safe is probably redundant as I really don't know how well it would survive a fire and is also the most likely to be out of date as the backup is a manual operation. I just can't put all of my trust into an external company that I pay $50/year to.
Great analysis! My wife and I went through this when our kids were born. Genetic diseases were the deal breaker for us. Basically, if you need stem cells, it's unlikely that you want your own cells that likely caused the problem to begin with. Also, the chance that one's cord blood is useful to another family member isn't very likely so that option is out as well. It really remains to be seen if private banking of any bio material will be useful when compared to public banks. In the absence of a major and specific scientific breakthrough, there is just no compelling reason for private banking.
In the end we donated their cord blood and, if needed, we'll use the cord blood bank like everybody else.