Not that I have that many (I wish!), but how would you store >100 Bitcoins? The easy answer is just to say "create 1 offline/cold wallet and put them all in". But what about risk management?
Suuurre, "uhh, I'm just asking for a friend." Joke.
It's a great question.
One person mentioned having a new address for each 5-10 BTC, I think that opens up more risk than it mitigates, especially if all those wallets are with the same provider.
You need to create a simple, logical, well thought through system that works for YOU!
Hardware wallet. Treat it like the vault that it was meant to be. Have extra wallets (not back ups), just in the box and ready for an immediate restore if needed. Keep multiple copies of the pass phrase in multiple locations and recite your passphrase words frequently, eventually they'll just be in your brain like everything else we remember.
If you're worried about tracking transactions use one wallet provider to convert fiat to bitcoin. Use another for daily/regular transactions. Use another for your vault. Get a debit card to make converting bitcoin back to fiat easy.
Don't leave watch wallet apps or accounts open on your phone or laptop. It's easy to set the "remember me for 30 days" option to bypass authentication on the device you use most regularly.
Consider using an IP address anonyminizer whenever you conduct heavy bitcoin transactions.
The key is that the system is logical and manageable for you. That way you'll never miss a step or forget something critical.