Ok, been having a great time getting red splatter all over my pretty pink car and seeing the sights, blowing up the folks, and figured it's a good time to list what I'd like to see:
1) Stealth that Works - I have a lot of fun doing the stand-up fights, but the stealth seems to be utterly broken. With max stealth, enemies with their backs turned can still detect you creaping along on the far side of a wall 20-30 feet away. I was hiding out on a rooftop when my stars finally went away, and a lone piggy that had been up there looking for me lingered after his buddies down below all took off, so I slunk up behind and gave him a colombian necktie. . .but the cops instantly sensed that one of their own had been horrificly murdered and just NEW it was me. The only place that stealth seems to work is in deathmatch (which I've seen people on here say doesn't work, but my knife an' shotty kill sprees say otherwise). Stealth kills shouldn't trigger retribution from omnitient AI, and a character being careful with maxed stealth should be able to pull of some shifty stuff, or at least, you know, not be instantly noticed by the untrained kid with the AK guarding a side entrace to the drug deal while he listens to his ifruit.
2) Offline Job Rosters - So, one of my favorite parts about the story mode was that when you popped over to a character, they'd be in an entirely different spot, like they were going about their business and had a life while you weren't working on getting them to the top of the FIB most wanted list. Sooo, combining that with the pick-your crew portion of the heists, I came up with what I think is a killer idea:
Have your characters be 'available' to do work when you aren't playing. Basically, your character can be 'hired' by other players to accompany on missions, race against, etc. The character doesn't gain any skill or RP, but going fee could be (level * 10 to 100) bucks or so per job, which the player gets, minus Lester's 20% of course. It wouldn't be at all game-breaking, but would be kinda cool to have buddies and crewmates riding shotgun.
You could set your availability even, default to not available, 'everyone', 'crew', or 'friends'.