Los Santos is fine for V, but for VI Hawaii would be awesome. Just imagine having all Hawaiian islands; you'll need a plane or a boat to travel between the islands; there big citys as well as forests, beaches and uncivilized areas. I think it would be a great experience to play GTA on Hawaii, it would be something completely new for GTA. It would be exotic but still in the USA. There'd be many mountains, huge highways and forests...
Rockstar would be foolish to create a game about SoCal and not include Mexican narco cartels in the storyline; with the war that has been raging on the US/Mexico border, and 40,000 dead in the last few years, itís a storyline that practically writes itself.
For example, the largest and most notorious Latino gang in San Diego is the Logan Heights gang. Itís a SureŮo gang whose members are actually hired, by the Tijuana Cartel, as assassins to kill rival cartel members in Mexico. These Logan Heights assassins are trained by mercenary military training schools to be as proficient as any paramilitary organization.
Watch this documentary on the Logan Heights gang and you will agree that it would make a great GTA plot; the Logan Heights gang member gets recruited to be a trained killer, travels to Mexico and gets involved in an international drug war.