I have some that are over 10 years old and still work. I have some that are much newer and have died. I have some that will no longer format. I guess there's no way to guarantee life expectancy of this media. What I'd do to improve the chances of survival is make more than one of each floppy and store separately. Keep them away from magnetic sources obviously...motors and such. Keep them away from excessive heat and cold and at a stable temperature....nothing really more special is needed but don't wait forever. Good luck..
I have a 10yearold desktop (a 386 under DOS 6) and have been backing up documents by converting them to ASCII and putting them on floppies for the eventuality of having to get a new desktop one day. I realize this is risky but could someone tell me 1)what is the life expectancy of floppies? 2)how reliable are they for ASCII text (assuming what's on the floppy is irrelevant), and 3)what is the best way to store floppies?
Thanks for your help.

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic