I think there is a very wide range of acceptable TravelBuzz! topics. Non-miles travel questions are welcome here.
The value of TravelBuzz! is that lots of people read and respond here.
TravelBuzz! is valuable because of the "network effect." That means that the more people read a particular forum, the higher the value of that forum.
If I moved every post that had a more specific forum, there would be very few threads on TravelBuzz!, people wouldn't see those threads at all, and the value to FlyerTalkers would be severely diminished.
Now, if TravelBuzz! gets too big and too busy, then it makes sense to start having people post to the other groups, e.g. London, airports, etc.
But until then, it is most useful to post where people read and respond -- which is here.
This is my personal philosophy and what I will follow unless Randy tells me otherwise.