I think prisoners should be forced to engage in more community, hands-on, and educational work, but also should be separated based on their crimes.
Torture should still be used on members of terrorist groups to reveal information on the activities on those groups, anyone who objects to this better bring some serious counter-argument.
Also, I think crimes that usually land people in jail but aren't horribly inhumane such as blackmail, extortion, unarmed robberies, possession of certain drugs such as marijuana (until its legal), and copyright infringement should get heavier fines and forced community service instead of actual jail time.