I was thinking about open configs and I think they could do quite a bit for leagues.  Leagues can lean away from doing a track twice in a season and instead add variations to the track to make it feel new.  I.E. FE Green can be run normally and with the new 'loop.'
Also, I was looking at the Fe Rally X (the longer one) and it looked like the Rally X Green's tarmac surface could be used as a sort of 'joker lap' if someone is really up to it.  
Honestly, I've only looked at FE and the possibilities seem endless.  I can't even imagine what things are like on Aston or South City.  Westhill is a bit of a drag though!