I recently received an invitation to a "U.S. Kavli Frontiers of Science symposium." I have to be honest, when I first received it, I kind of thought it was conference spam, but investigating further, I came around to thinking it seemed legit (in part because it is organized by NAS and they offered to pay expenses).
But "is a legitimate scientific activity" is a pretty low bar for deciding whether it is worth expending one's limited time to attend a conference (at some minor personal inconvenience), which at least for me is not obviously connected to my research or even necessarily my discipline. Does anyone here have experience with it? Are the talks interesting for outsiders to the disciplines? Is it actually a good networking opportunity? Is it the sort of thing I should be bragging to my dean about (I'm about to go up for tenure, so bragging rights are somewhat relevant)? Is it just sort of a glorified TED?