The free portion of the Flight will let you fly over Hawaii County, and in the same day they will release the Hawaiian Adventure Pack. It will add the rest of the state, several bonus missions and Vans RV-6A. The price of the Adventure Pack-and will be 1,600 Microsoft ($ 20 | £ 13.60).
I'm still angry that they didn't invited me in beta. : D
UPDATE: Ahh there will be any additional aircraft which will be released as another DLC (other than Hawaiian Adventure Pack-a).
Here is a video with flying developers: