I loved Mitch Joel's recent take on the death of the unconference, and share his regret that these types of events appear to be waning. I've been to several of these - some good, some bad. Most of the ones I have attended seem to have sputtered and stumbled under their own weight - with too many people in a room, self-organizing can become a wincingly painful exercise. Mitch is exactly right to call out the various unconferences that are really just poorly organized conferences by another name. I would much rather attend a well-curated conference (like Explore, or Social Slam) than be thrown into a room with 250 random, undirected people and hope for the best. Maybe it's the term "unconference," though, that gives pause. Once you use the word "conference," you enter a mindset, regardless of your intent, and with that mindset comes expectations and assumptions that may work counterproductively to your goals.
There is another model: the Renaissance Weekend. These were popularized by the Clintons, who staged their own Renaissance Weekends before and during their ascent to power, and are meant to be "festivals of ideas," led by the participants, showcasing private, off-the-record explorations of possibilities. Of course, these are hardly "unconferences" either, as they are typically at least somewhat programmatic.
The actual, "official" Renaissance Weekends are by invitation only, and I've yet to find myself on the invitation list. :) But, I have been fortunate enough to have been invited to similar gatherings, and to me, the best of them suggest an agenda, but rely on a small, carefully curated attendee list, and not a "program," to drive the discussions.
So, here's a thought. If you find conferences too generic, and "unconferences" too disjointed, think smaller. Remove the word "conference" and you stop thinking about how many cookies to order, or finding event space. Instead, think about who you'd want to learn from, not what you'd want to learn -- the hallmark of serendipitous, undirected knowledge discovery -- and plan a weekend. It only takes 6-8 interesting minds to create the experience of a lifetime, and the group need not hang together in any kind of "mastermind" fashion after the event, though they certainly could. Save the money you might spend on conference/event facilities, and use it to fly that incredibly interesting person to your group instead.
The only rule of the official Renaissance Weekends is this: Civility Prevails. I have to say, I vastly prefer this to "the law of two feet," which I find uncivil. If you aren't getting value from a Renaissance Weekend, getting up and leaving is the worst thing you can do. Contribute, instead. Ask provocative questions. Prepare to be challenged. And rely on the quality of the people with whom you are sharing the experience to make it worthwhile.
Also, turn off Twitter. You're welcome.