Ha ha! It has indeed been a long standing conundrum. And one that I have hopefully resolved for now.
Yes, I think a savings jar function within the wallet is a good idea. You could set aside funds for certain purposes or for certain people that you didn't want to mix up in your general funds balance.
In terms of paying interest that's usually only reserved for funds that are staked in some capacity but I would want immediate access to the savings jar so I can pay the tips out. I have no problem shifting funds from the jar to my main liquid balance in the wallet but I need that instant access feature.
We already have the savings part of the wallet of course, but interest is only paid on the HBD balance not the Hive balance. It would be wonderful with the addition of a new savings jar with instant access which could pay a small rate of interest.