I'd like to change my previous sequel ideas, btw.
Pre TA2: IM3, Thor2, Cap2, BlackPanther, Edgar Wright's Ant-Man
TA2: Ultron gets set up in all these films as a product of all of the heroes, so he's personal to all of them (ie, Designed by Pym, Vibranium body, built self at Stark facility, Cosmic Cube Power Source lost by Thor, made self aware by discussion with Cap), at which point he turns the whole world upside down via some uberhacking and then brings it to the Avengers personally, threatening family members bringing back villains (ie, letting Abomination loose, finding Red Skull, remotely controlling the Iron Monger) putting them at each other's throats. BP joins at the beginning, Vision at the end. Carol Danvers is supporting cast in SHIELD, but no powers. One Avenger tragically dies in the climactic battle.
Pre TA3: Dr. Strange, Thor 3, Cap 3, Guardians of the Galaxy
TA 3: Ms. Marvel now has powers and Thanos intel from GotG. One Ant-Man or another has joined the squad in a relatively minor Hawkeye-sized role. Thanos, now built up and explored in the GotG movie, wages war on everything, Asgard falls, the world in almost complete shambles, nothing left but to fight with everything they have. Very much a war movie, with a combat-lighter background quest, like Lord of the Rings: Return of the King, that pays off and wraps up every single storyline.
Pre TA4: BP2, IM4, Iron Fist, SHIELD
TA 4: Establishes the Avengers as a SHIELD-sanctioned team that Fury keeps on call, can call on selected operatives to deal with world-class threats as needed. Perhaps they'll fight Kang in this one.
Post TA4:BP3, GotG 2, IM5, Heroes for Hire, who knows, y'know?
TA5,6,7: Continue this cycle, perhaps as a trilogy dealing with the Kree/Skrull("Chitauri?") War, with Ronan and others, Disassembled, and maybe even Korvac.
TA8,9,X: If it gets that far, call me.