You don't have to use MultiBit. Go to
www.bitaddress.org, generate a few paper wallets, print them out and keep them in a safe place. Split your funds between them and then import private keys one by one when you need to spend your coins. This is possible with multibit but it's easier with blockchain.info's wallet, Electrum and Armory.
I'd stay very far away from MultiBit at this point. It requires Java, doesn't have deterministic wallets and has a nasty coin-eating bug that bit me and others.
Smart users usually choose Armory or Electrum.