I keep saying it but North Africa through to Italy would be ideal.
We can get P-40s and Macchis and big cannon armed Hurricanes and P-51s all in one big shot. Mind you it'd be the P-51A or the A-36 at first but that'd be very cool. Plus the way everyone wants to fly aircraft the P-51A's superb low level performance would be perfect.
I remember them saying that early Africa would be the second release, it makes sense as most of the aircraft are slightly later versions of the ones we currently have add to that some new ones which could then form a basis for the third release of maybe a later africa or a return to thechannel front.