May I add some input to your topic?
A purely rhetorical question I realize, but i wanted to add to this topic from my experiences, and viewpoints, and I hoped you wouldn't mind.

For the record, let me say, that, I have absolutely no experience, at all, in anything having to do with the College experience. Perhaps that is why I feel so confused in reading the Posts in this Topic.

My experience with Support Groups tends to be groups such as Alcoholics Anonymous, Narcotics Anonymous, Emotions Anonymous, and Celebrate Recovery. These were (and are) all chaired by nonprofessionals. I no longer attend any of these groups, and when I did, was usually because it was a requirement of several Recovery Programs that I happened to have been involved with over the years. They are also known as 12 Step Programs in that there are 12 steps, or guidlelines, if you will. I'm quite sure there are many other other Support Groups out there, based on some version of the 12 Steps. http://en.wikipedia.org/wiki/12_steps

So, my experiences with Support Groups have all been based on Recovery, whether recovery from alcohol or from drugs, it's all about staying sober/clean, and how to live a life without using booze or drugs.

In my view what you all have been describing is Group Therapy. http://en.wikipedia.org/wiki/Group_therapy, though I know that y'all distinguish between that and a Support Group. http://en.wikipedia.org/wiki/Support_group.
I personally am having a real hard time in separating the definitions. Though I must admit reading the Support group wiki made me realize that my understanding of Support Groups is very limited. But might I also suggest that your definition of a Support Group may also be limited?

I've never been to a Support Group that was facilitated (or chaired) by a professional, but all were more or less led by an actual member (or members) of the group itself.

"I guess what I'm asking for is a better understanding of what a "good" support group might look like, so I can compare my experience against that"
To that end may I suggest that you find what is termed an "Open Meeting" of either an AA or NA Group meeting. http://alcoholism.about.com/cs/meetings/a/blclosed.htm
http://www.na.org/?ID=bulletins-bull15-r