Hi Buggirl - good post!
I went to AA at first because it was mandatory, through my treatment center. After I got out of treatment, I went every Sunday for a while. I stopped going because I felt that AA was not a great fit for me, long term.
I am working on 3 years of sobriety. AA was in my life for about 6 months total. That said, I do view AA as a big part of helping me get the ball rolling. While I no longer go, I like to know the local schedules, and meeting places, just to have them in the back of my head in case I need them. It's a "security blanket" thing for me, I guess.
For me, AA isn't mandatory. But sobriety is. Just because I stopped going, doesn't mean I can't go back anytime I want. That's the cool part about AA!