--twin towers, i think you should have a choice if you want the twin towers back in the game. make it feel more like new york. i dont know, that file might be a little big.
--the cheetah, what happend to that car? it was one of the best.
--more virsions of cars. like more than one type of infernus. one from GTA3 and vice city, better graphics of course.
--someone said something about a seat belt. i dont think that should be a cheat. maybe you can press a button once in the car to make niko put the seat belt on.
--bring back the side views! its so annoying without them.
--car modifications
--parachute
i cant think of anymore right now.