Hi,
Only a quick reply as I'm in a rush, but on the King Air theme, if you think that the main business centres (and thus charter requirements) are the main conurbations - there aren't that many which suffer from a lack of suitable aviation facilities which won't take jets.
It's only with really picky clients that they insist on the really small places.
Short sectors though, the King Air is still a very useful bit of kit, I'm not trying to talk it down, merely saying that prices these days are low enough as they can be on jets and most people would opt for the jet and a slightly longer road journey to the aircraft.
Sorry if that doesn't make sense, am typing quickly.