"...a tentative go-ahead to discuss plans for another unconference in 2016" - Yay!! Best news I've heard all day!!! 
The facility (rooms, tables, chairs, etc.)
Overall I thought the facility worked pretty good. No real complaints, but I would like to say that going forward it's important to make sure we can rearrange furniture (possibly clear the room like we did for @clong 's session) as needed and be able to hang stuff on the walls!
The facilitation (did it feel (dis)organized enough?)
I thought there was just the right amount of facilitation. Not too much so we felt stifled, but just enough to keep everything going in the right direction.
The promotion (what did and didn't work this year?)
Need a LOT more promotion. I'm not kidding, pretty much everyone I talked to about the Unconference had no idea what I was talking about. Even afterwards a lot of people I talked with were surprised that there was one and disappointed that they missed it. I understand that Instructure might not want to cannibalize from it's pre-conference workshops, but even a little promotion would go a LONG way. Most Instructure employees helping at InstCon didn't even know about the UnCon or where it was at. 
The dialogue / conversation
AMAZING! This was by far my favorite part of InstCon (including meeting Olivia
). The conversations and discussion stretched my mind, my beliefs, and my assumptions about teaching, learning, and technology (using Canvas and other technologies). I got a lot of great ideas that I'm planning on using this fall with my hybrid course and overall was invigorated by the discussion.
The logistics (timing, group size, etc.)
Timing was pretty good. I was fine with it running the morning/afternoon the conference started, but I'd love it if even more if we could get an Unconference track running along side the normal sessions throughout the conference. Or at the least a meet up the evening before (Monday evening, then all day Tuesday?). Group size was ok before lunch, but could have been a bit bigger. After lunch a lot of people didn't return (I think a number of them had pre-conference commitments), but those who stayed were a pretty awesome bunch and I still got a lot out of the sessions.