If you're worrying about which data storage medium would be most likely to survive a fire, you've already lost. It's about as stupid as getting a circumcision to avoid getting HIV.
Since you're asking Slashdot for advice, you can't be that big of a deal, which means you need to protect against idiot script kiddies and basically nothing else. Any meaningful adversary wouldn't hack you, but rather confront you through blackmail, seduction, or just plain old hitting you with a crowbar. If you are a big deal, or have ties to organized crime or other significant risks (just covering all the bases here), then what the hell are you asking here for? Hire a competent security professional; ask Slashdot for tips on finding one of those, if you must.
Now that this is established: what you do is you wad up your files with whatever you want (tar, zip, whatever you're comfortable with) and use AES (or CAST5, or whatever). Then, if you really want, you can etch the key into a big piece of steel or stone and put that in your safe. Using the alphabet {|, -, /, \} for ease of carving and to avoid ambiguity, you can represent it in 128 strokes. Assuming 2"x2" space for each one (including border), that's about 3.5 sqft, or ~5 sheets of steel in US Letter/A4 size. A more sane thing to do, might be to store copies of the key on paper in the bottom of a locked filing cabinet stuck in a disused lavatory in the basement of one or more of your friends' or family's homes.
By the way, I find it hilarious that the same crowd which once would have told you to encrypt and store remotely is now tripping over itself to find ridiculous reasons not to, just because it's easy enough for anyone to do now.