The off-road checkpoint missions in GTA III (Patriot Playground, for example). They are just BS and a waste of time.
Also, in VC, the mission where Tommy had to get a driver for the heist is like the most pointless mission ever:
-Hilary will be the driver if Tommy beats him. If Tommy beats him, then what would be the point of hiring him as a driver, if we already know that Tommy is better?
-It's just BS the fact that he has a Sabre Turbo and we are forced to use a stupid Sentinel. Not even the XS version. That's BS. At least in III we could pick our car for races.
-Hilary just shows up at the end, then gets out of the car and gets killed in 1/2 second, then Tommy drives everyone back to the safehouse. I mean, really?
Might aswell remove Hilary and every mission regarding him from the story. Really, it would suffer little to no changes.
S.A.M. is not bad designed, but it's hard as f*ck. Either I miss hitting the plane with a rocket or I get run over by it.