I'll make a list (order of thougts, not importance):
1-) More realistic money. I mean, who gets 10K for blowing up people with a RC, for exemple ?
2-) As everyone, better crash effects
3-) Less, a lot less cloned pedestrians
4-) New rides
5-) New car modifications. I know it's not a NFS game, but, if they keep the tuning car thing, they should upgrade it.
6-) A nice and sensed storyline
7-) Clothes shops. GTA's a life-like game and I think it would add more realism to be able to change outfits.
8-) Easter eggs and other stupid things that R* can make. Funny stuff like when CJ gets raped by Catalina.
9-) Better AI cops. I'd like to have no more "You-hit-someone-in-the-face-I-pull-my-pistol-and-bust-'till-I-run-outta-ammo" kinda like cops. I'd prever to see cops who, as long as you don't pull your gun out, they'll do the same. Or they pull it out, but not fire it, just tell you to stop. It's weird, but I'd like to, if I want, be able to surrender and not using brutal (or bloody) force. It would add realism, don't you think ?
10-) No more feeding, no more gyms ( I'm pretty sure there won't be, but who knows)
11-) A lot of side missions who are related to the storyline. I mean, who thought that Vigilante and Paramedics missions ever fitted in any GTA ? Me, I've never. Yeah, it's cool, but, it doesn't fit.
12-) I'd like to see cops protecting me. I get into sumkinda trouble (I get shot), I fire back and a policeman sees me, he should only shot a me. But at those who fired first, y'know m'sayin' ?
I think it's about it & yeah, Fatalgamer, it's R* North