The only issue I see with these last two ideas is that we already have an extensive underground network for manufacturing, transporting, and selling this stuff. Aren't we blindly assuming that these groups will begin following the law? I think we'd have to make sure that it was more profitable to follow the regulatory guidelines than to skirt the law. Also, there will be groups that won't go through the trouble of government hoop-jumping and will continue to sell it on the side, or they will undercut the legitimate businesses. Basically, I think we'll continue to have this war on drugs in some form simply because the illegitimate means are already in place.
I'd still like to see some discussion regarding prescriptions as well. Should a person be able to stop by CVS and get some OxyContin for recreational use, or should they still need a prescription? What sense would it make to legalize heroin for anyone to use, but not a prescription drug that can be used for the same purpose?
I think, without delving deeper into history and the end of prohibition, that the black marketeers would soon be either put out of business or they would legitimize they're networks. Think of it like this, if Sally and Biff want to share a bong, why go through the trouble of setting up a clandistine meeting with black beard if they can skip down to the corner market and buy a half ounce. Convenience stores charge higher prices than grocers, yet you don't see underground slushy markets. Sure there would be some growing pains working into a new system, but I believe that IF the long arm of uncle Sammy is kept out as much as possible, things would iron themselves out fairly quickly.
As far as prescription drugs are concerned open the doors. Put an age limit on it and make people sign waivers if for recreational use (med use could still be prescribed) if they have problems, it's on their dime for treatment. If they can't pay for treatment they get dried out the hard way. In the pokey, while they are making small rocks out of big ones. If they survive good, if they don't. They chose badly.