Liz, we're not career counselors here, and don't know what is right for you.
But I can say that I worked in a rehab for a couple of years and it was one of the most rewarding jobs I ever held. My son is an addict, I work my own 12-step program for codependents, and I had about 10 years recovery before I took this position. I don't think I could have done it well with less than that.
That said, the executive director had no addiction experience personally, but had a degree specializing in mental health. He offered a good balance and was a good source of knowledge because addiction and mental health are so closely connected.
What may help you decide would be perhaps do some volunteer work at a detox facility or rehab, and talk to the staff there about their backgrounds and experience.
Good luck in your career, whatever you choose.