Single Player Wishlist
More side quests like the previous games or Chinatown Wars, slinging drugs, building up an empire, taking over territories. Why these things were missing from IV was beyond me. Imagine doing side quests from The Truth where you have to cultivate weed so it can be processed and sold, or it being important for your cartel to have certain buildings and chemicals for distribution, then consider doing the same missions from the side of law enforcement, finding and stamping out those fields The Truth put so much work into, or busting meth labs out in the boonies in Vigilante missions that affects the news and perhaps the over-arcing storyline.
A return of bicycles, I kid you not some of my favorite moments in San Andreas was coming out of a heated police chase, gang battle, or particularly hard mission just to wheel around the beach or country or even inner city on one of the bicycles, it provided a nice change of pace to the "Go! Go! Go!" of the rest of the game, plus it gave you time to slow down and enjoy just how much work was put into the AI and animations the R* team put into creating a living breathing world.
A return to car improvement/modding, custom paintjobs, upgrades, rims, maybe a little something extra like spending some ungodly ammt. of money (Say a million or so) to upgrade it to bulletproof, or lighter and better handling, faster.
A return of Police Motorcycles: HPV-1000 and Wintergreen were my favorite vehicles in Vice City and San Andreas, having them cut to the multiplayer in The Ballad of Gay Tony was a let down.
Police Helicopters with a working spotlight that just kind of locks onto peds or cars the game thinks you might me looking at based on where the camera is would be nice, turn it on/off like you do with high beams.
Max Payne 3 multiplayer style Weapon Upgrades, adding lasers, scopes, replacing internal parts to make it a lighter loadout or silencers to weapons logically able to accept them.
Less modes: One thing I think I noticed from GTAIV was that almost no one wants to rank up playing the other modes, I for one have sat for the better part of twenty minutes waiting for someone, anyone to show up for Cops and Robbers, Red Dead Redemption style Free Mode had it so it was all fairly centralized, and choosing those modes by going into the turf you want to capture and challenging everyone else to take it from you was pretty boss, don't really need to say more about it than that but I really liked the way that was done, with lobby toggles for turf modes perhaps because you know one idiot will sit there and challenge everyone every two minutes for three hours straight. >.>
Better police AI, sorry but the appropriate answer to bumping into a police vehicle isn't three cops with shotguns turning the inside of your car into a fine red mist. D: Then again LCPD is kind of rough... but yeah.