This way you'd get a unique map shape, anchored by the city to the west. There would be plenty of wilderness, with two national parks on the two ends of the island. Santa Rosa and Vacaville would perfectly serve the roles of secondary locations. Though mountains are sparse, the landscape would be broken up by the occasional lake here and there.
And yes, there is indeed a settlement near Sacramento called "Yolo". Let's move on now please.
Crime
Whatever points we docked Sacramento for geography, it's going to win back in terms of crime. Not only has the city consistently had an above-average violent crime rate, but in 2015 and 2016, rates have been on the rise — what's more, in 2015, Sacramento saw the largest rise in crime rates among all major cities of the USA.
There was a greater than 25% increase in violent crime rates between the January and June of 2015 compared to the same period in 2014. If you're interested in hard data, the violent crime rate in the city hiked up to 379 per 100,000 residents, placing it well above national averages.
Sacramento has seen ever increasing rates of gang activity. While California is pretty well known for the influence of various criminal syndicates, the other two big cities are most often associated with gang activity. Nonetheless, much of Sacramento's crime can be chalked up to gangs.
Drug trafficking is a major illegal business. Though much farther from the Mexican border than San Diego and Los Angeles, Sacramento is still an important link between the USA and the Mexican cartels. Weapons trafficking also prominent in the city.
Corruption is also a major issue in Sacramento. Due to the decentralization of government agencies, "taking a bit off the top" is made much easier, officials also have a greater chance of getting away with it. With the proliferation of white collar crime, cooperation between corrupt officials and criminal syndicates strengthen both sides.
Recognition
In a returning theme, Sacramento is overshadowed by its larger and more popular counterparts in California in terms of recognition. While the cityscapes of both Los Angeles and San Francisco are iconic and instantly recognizable for even foreigners — which is probably why they were chosen as GTA settings before — Sacramento just isn't that easily identifiable.
In fact, one of Sacramento's most recognizable landmarks when viewed from afar carries the same name as another similar, and much more famous landmark. The Tower Bridge is a a large yellow, metal vertical lift bridge spanning the Sacramento River. It also looks absolutely nothing like the London landmark of the same name.
Other notable landmarks, which would look particularly good in a virtual environment due to their unique shapes, include the Ziggurat, an oddly built office building; the West America Bank Building and the US Bank Tower.
Historic landmarks in the city include Sutter's Fort, which was mentioned before, the Eagle Theatre, which was the first permanent theatre in the whole state, and the Big Four building. The latter two are reconstructions, as their original counterparts were both demolished.
Other notable landmarks include Raley Field, the City Hall and the California Capitol building. The Capitol bares a strong resemblance to the White House, which isn't coincidental — it's based on the US Capitol Building in Washington D.C.
All this considered, the city isn't particularly well known overseas. Even if certain buildings would be telling for American players, chances are few foreigners would be able to identify the city off-hand.
Potential Story
Not much about Sacramento really stands out which would immediately suggest a storyline. That said, Rockstar may draw on the ever increasing crime rate as well as the gang activity. One possible route would be for them to take GTA in a direction it's never gone before.
The protagonist could be an undercover cop, tasked with infiltrating the criminal syndicates of the city in an attempt to feed the police information, to help them curb the rapid increase of crime. Secretly, the protagonist would also have a personal motivation, as the leader of the syndicate he infiltrates personally executed his partner years before, and he wants to exact revenge by tearing down the boss' organisation around him.
Due to his own motivation, the protagonist would not "go easy", and is willing to take even the most destructive and brutal jobs for the syndicate in order to gain trust. Meanwhile, unbeknownst to the protagonist, there is a corrupt element in the police department working with the syndicate, however for their own reasons, they don't reveal the identity of the undercover cop.
Eventually the story would become a tangle of motivations and double-crossing, with threads running between the protagonist, the honorable police, the corrupt police and the syndicate. Eventually the corrupt element approaches the protagonist, offering to help him exact revenge in exchange for handing over control of the syndicate.
The second-in-command of the syndicate learns of the protagonist's identity, and instead of blowing his cover, offers an alliance. The protagonist has his vengeance without dismantling the organisation, and hands control over to the second-in-command.
The protagonist would be faced with a choice: help the honorable police, the corrupt police, or the second-in-command? Either path chosen would require them to perform jobs for the syndicate, thus enabling typical GTA-esque missions full of gunfights, violence and thrilling car chases.
The game could also feature a reputation system, introduced after all three potential allies reveal themselves. Certain side missions, as well as various choices made during main story missions would sway you towards one of the three allies, granting you greater bonuses if you eventually choose their ending.
For example, if a side-mission has you intercept a weapons shipment from a rival gang, you can either submit it as evidence (thus helping the honorable police), hand it over to the syndicate (thus helping the second-in-command) or selling off the shipment to a third party, depriving both the syndicate and the police of the valuable haul (thus helping the corrupt police).
Final Verdict
B-*'Pros : Story potential, crime rate Cons **: Unideal geography, relatively poor recognition
Sacramento has some beneficial aspects, such as the pretty good story potential as well as the ever rising crime rates, however overall the less than prime geography coupled with the potentially poor recognition among foreign players places many cities above Sacramento. Maybe for a spin-off?
Would you like to play a GTA game set in Sacramento?