In the case of 100+ BTC. I's very simple. 2 things. One, you want to keep an eye on that, so as they don't just disappear over night. Two you want that off-line, far from the prying hand of hackers!
My suggestion, is break it down into 4 paper wallets, generated off-line, 25+ each. Each using a unique pass-phrase or password. Paper wallets are stored in a plastic zip-lock bag for moisture protection. The private keys associated with their corresponding public key should be copied to a SD, USB, or a removable media device by an off-line computer, and that to should be zip for moisture!
Paper wallets can be stored in a safety deposit box, along with the SD/USB device at a local bank. No sense in banking crypto if your gonna have a version hanging around the house.
The four keys should be installed in view mode only on an Application such as Mycelium, or links to the blockchain should be created in your browser, as to keep an eye on them as you move from day to day!
If long term banking is required, then only passwords can be kept around the house, say in a cookie jar, picture frame, etc.
Enjoy crypto man it's alot of fun!