Yes, legalize it.
Properly regulated, taxed, and distributed, we'd free immense space for prisons in America to house real criminals (Violent Offenders, Hard Narcotics like Meth and Cocaine, etc.), and not have to cut loose sex predators who prey on children/teens at a mere half or less of their term being up.
The taxes would go to greatly improving the economic status of the nation, as where marijuana users have to rely on getting to a safe and discreet back-alley or red-light-district dealer who charges twice the price for half the weed (While not telling them the weed is only half Marijuana and is cut with worthless dried herbs/grass), government regulated marijuana sales, despite being taxed, would likely still be cheaper economically because for a little more than one used to pay, they get all marijuana and no inert/worthless random shrubs.
Regulated sales to only those whom are legal adults (Alcohol and tobacco's "21 or over" laws ring a bell?), and restricting use to private residences (Many states/counties have public consumption of alcohol as a misdemeanor offense punishable by several applicable fines and repeat offenses with a felony charge, and of course the "No Smoking" signs in literally every public restaurant and such) will help as well.
Entrepreneurs could also open "Weed Friendly" bars, and will apply for a state liquor and/or Marijuana license to sell their products, making way for new jobs in many communities.
The economical and societal good it could potentially do is near endless, while the expenditures and effort made to stonewall what is essentially Alcohol delivered like Tobacco into the body is pretty pathetic.
Alcohol is a depressant substance that impairs vision, reaction time, decision making, etc., and marijuana is proven less physically addictive than caffiene (Any of you who've had an energy drink or cola in the past day might feel the effects of wanting more of it, and with Marijuana, you wouldn't as much if at all).
And I don't see how marijuana users who drive while high could be nearly as bad as drunk drivers. They enter a VERY relaxed state, get the munchies (Or dry-mouth symptoms), slowed reaction time, but in the friends I've talked to, none of them had impaired vision, and while they were a bit "slower" mentally, they still were able to remain rational and coherent to an extent far exceeding those whom suffer alcohol intoxication.
The one friend I had who was a regular user used to be one of the friendliest guys around. A few months after his father passed away, he became very bitter and caustic, and eventually ticked our mutual friends off enough to where they had him banned from all three of their forums they had together, even the one where he was the one who came up with the name of the forum.
Aside from him, a great many marijuana users I know are very friendly and honest people, indulge in moderation, and are very adamant about ensuring they never drive while "toasted" (Their term they like to use).
I've heard some people lock their car keys into a small box, give it to their "Designated Key Keeper", whom is not allowed to unlock the box and retrieve keys until the next day when everyone has come down and had a good night's rest and/or some coffee.
A majority of marijuana users are far more responsible than many alcohol consumers in my experience.