I think GTA4 should be an entire country, but not a very large one, just a small one with Liberty City, Vice City, San Andreas, and I think the other city should be a Detroit like city.
And its more realistic with seasons, like you go through the entire year, and you can get snow in the winter, rain, thunderstorms, tornados in the summer, etc...
And since GTA4 will obviously be on the PS3 probably, and using blu-ray discs it can hold up to 25gb single layer and 50gb if its dual layer, so they can pack alot of information on that disc.
And because of the space, they could have alot more cars and other vehicles.
And another idea would be if you played as Claude at present time(2007?), and he can talk, and you could possibly do work for Tommy Vercetti in Vice City, and Tommy is a drug lord, like around 45-50 years old.
And since each city is an island, you can just fly from each city, or possibly have bridges that connect all the cities.
And in each city there is a different climate depending on what time of the year it is, like it could be snowing in Liberty City but be nice and warm in San Andreas.
This should be the next Grand Theft Auto.
