I would really would have loved to see Staten Island. It may just be suburban sprawl, but I was never I big fan of Alderney (which was what pretty much replaced it) and feel that Staten Island would have been a lot more eye appealing.
I would have liked to have seen Staten Island, too. Some of the parks there are probably as close as you'll get to countryside while still being in New York City, and that would have made the people who still wanted countryside a little happy I'm sure.
A stadium in Bohan or Dukes for the LC Swingers would have been nice, too, considering it's mentioned as existing and yet it's nowhere to be found in the game.
And hell, I'm sure whatever the original map was for Liberty State would have been amazing. I wonder what that map looks like, and whether or not they probably plan on using it in a future GTA (maybe they want to, which is why they haven't released it anywhere even though it was a scrapped idea and we've seen early beta maps of other GTAs before).