Grand Theft Auto: San Andreas already has a mechanic which can be adopted for this travel feature. All three of the first 3D Grand Theft Auto titles featured large airports (and GTA: San Andreas actually had three of its own) which would be the perfect way to let Carl Johnson stretch his legs in Miami, or allow Tommy Vercetti to return to the town that abandoned him. If the rumors about a Grand Theft Autotrilogy are true, it would be nice if Rockstar allowed players of any game to travel between Liberty City, Vice City, and San Andreas at will.