Beat it, all 3 endings... Pop'n Trevor allows you to split his cash between Mike and Frank (a dirty way to make millions)...
I'm currently leveling in GTA Online (I went ahead and forked out for the 12 month gold get 2 months free deal).
I Really need to join a crew though... get'n hard to level past 90 doing solo runs...
Then again I hate the level 5 tards that try to shoot me when I'm play in an open server (and they hate the sticky bombs I drop as I drive away
).
Note for GTA Online users - quick leveling by finish the survival oil refinery (multiple places to camp).
Doing it solo can be done in about 20 minutes and will net 20k plus 2800 to 3500xp (along with all the weapons and ammo)... Rinse repeat and you'll max out the shooting option and level pretty quick.
The only weapons that do not show up in a full 10 round run of survival are the automatic pistol, advanced sub machine gun, and regular sniper rifle. The Barrett .50 cal shows at round 5 or 6, grenades, grenade launcher, rpg, minigun, all 3 assault rifles, all 3 shots guns, 2 MG's, and at least 1 pistol are all in a single 10 round run of survival...
Also you can quickly level by running races (even by yourself), but it costs $100 for each race (plus side is you get full heath and armor for that $100 so it works out).
Oh and the Buzzard Attack chopper spawns in game at around level 50 (on top of the hospital, and the different air fields).
If you see me in game (BringtheNoize) leave me alone and I'll do the same
Oh and if you want to be a real Ass in GTA online...
Go get a fuel tanker truck plant a sticky bomb on the tank/trailer then drop the trailer in front of a group of people and drive away, then hit Left on the pad when you are safely away....
Or once you hit level 50 or so call lester and have yourself vanish, then set ontop of a building with a sniper rifle and cause havok to other players in the area (use a chopper to get there)...
And no I haven't done either, but I've thought about it a couple of times, but I like the extra money coming in for being a "Good Sport"...