Prisoners need to be disciplined. They are. It's really up to the person who runs the jail.
If that person is a good person to run the place, then the prisoners will like them and be better behaved and generally happier.
The prisoners should have to work to get television (ie the the televisions are powered by bikelike generators).
their food shouldn't be bad just because they did bad things.
they should get therapy.
they should get pretty good healthcare.
they shouldn't be in cells with too many people. three at the most, mixing and matching so that if two get in some fight, the other can maybe stop them or something.
Heck, you can even use prisoners to test medicines and such, that'd be a neat idea.