Jim, it all depends on your area and what or who has the largest presence. You need to look at the local chapters and what they do or don't do. Go to a chapter meeting or two before you decide. The chapters are the backbone of any HI orginization.
If you want to see some of what ASHI does go to the ASHI Reporters website and look at the back issues,
August 2007 | ASHI Reporter
A ton of information can be found as well as an inside view into ASHI.