I think most should be decriminalized. As for side effect crimes, such as burglary, theft, etc., those are crimes unto themselves. It can be treated like alcohol, as far as driving; i.e., driving under the influence. But, especially, to jail users solely for using drugs is ridiculous and a drain on an already bloated state.
Employers, of course, can still drug test as much as they want. It will be up to the person to decide if they want to be employable or not. That goes doubly for government programs, although I imagine the ACLU and dummies would be the veritable hornets nest if you add drug testing to welfare requirements. But since we're hypothesizing anyway, add that to the mix.