What are your opinions on the characteristics of a circuit which promote overtaking? I reckon you need this sequence: slowish,shortish,simple corner --- long straight --- simple corner. Hence, Bahrain should be great, China & Turkey not so.
I think having a very basic, slow corner before the straight is crucial for modern F1, because of the relatively low importance of aerodynamics. The new and abandoned Osterreichring is a good example: dull track but some great races with overtaking almost every year. There's almost always overtaking at Brazil, too. The old Hockenheim after turn 1. But Monza and (old) Barcelona have long straights and little overtaking: the corners preceeding them are all too tricky for the following car. Ditto Suzuka. Malaysia-long long hairpins.
PS. Has anyone found a map of the revamped Barcelona layout? I don't like the sound of Webber's comments.