Personally I'd like to see Holland-like (Amsterdam?), Germany-like (Muenchen?), UK-like (London?, Edinburgh?), and other American-like locations. Not real names, and they'd have to be islands, of course.
A massive map where you really do need airports to visit the different places. There'll be enough space on the discs they use to have more than 5 San Andreas sized maps, and bigger than San Andreas ones at that. (I am actually just guessing though).
I hope they utilise that.