For information benefits from more direct routings, you could have a look at the Eurocontrol Performance Review:
http://www.eurocontrol.int/prc/galle...s/PRR_2006.pdf
No-one is (yet) talking about aircraft flying Great Circle, but tidying up European airspace, redesigning the airways network according to demand rather than national frontiers, more flexible use of military airspace and improving the capacity of the system to allow most aircraft to fly at optimum altitude/speed as well as most direct route, will save the industry millions if not billions of € per year - plus cut down hugely on CO2 emissions.