I honestly think you're better off with a safety deposit box and some acid free paper. If someone has unfettered access to that room there are far more valuable things than a bitcoin wallet.
Really depends on how "cold" you want the storage to be. I wouldn't want to have to go to a bank vault if I decide to use my coins, so I use offline Armory as a compromise between safety and functionality. I don't have that many bitcoins though. If I was holding a large amount I'd definitely go with your suggestion.