I actually wouldn't use a paper wallet. I'd get a small USB stick and create a text file. Then add the private keys to the text file and put the text file on the USB stick.
Throw the USB stick in the safest place you can imagine and you've got yourself secure holding.
USB sticks aren't very reliable, especially for repeated use.
If you must use them, I'd suggest at least 5 USB sticks and you can normally get small ones in packs of 20...
Hard drives also demagnetise themselves after 3 years (or begin to) if you don't rewrite the entire data.