I think the only even semi-workable proposal there is to ask people to make their thread titles crystal clear. Segmenting individual airlines in to 5 sections just isn't feasable. People can't agree on the appropriate forum to post topics in now when they only have Buzz/T Talk/Spam/Omni/News/Community/Airline to choose from. You are talking about giving them about 600 options! The situation would change from people being overwhelmed by the massive amount of posts to overwhelmed by the massive number of places posts could be.

What might help is if/when webflyer sets up a sister board to deal with more general topics like specific cities, where to eat in..., where to stay in...., whats the airport in... like, etc. A comprehensive FAQ for topics that are visited again and again might thin things out.

Other than that, I actually think most of the specific airline/hotel/car/credit forums are well focussed and easy to use. UA might be an excpetion (and I don't read CO), but, for example DL, BA, Amex, Hyat, Hilton are all quite user friendly.