Where can I put my money that won't make me angry?

All true, except that it does not take into account the value place on utility and access (or liquidity). A tenner in a savings account is easier to access than extending debt by a tenner.

Depends on the savings accounts you buy, I suppose. I mean if you're a spaz like me you get the really restricted savings accounts where you lose all your interest if you even so much as consider removing a single penny from the thing and putting it back the next week.

Notes under the mattress is the ultimate in liquidity though!