Take a comic book that hasn’t been made into a movie yet and make a trilogy of movies.
Green Lantern - the first movie would be the origin, of course, and showing Hal getting used to his powers.
Green Lantern II: Emerald Twilight
Would be based on the story arc from the comic, except I’d drop the “Reign of the Supermen” tie-in and make it a separate story. Coast City is destroyed while Hal is away from Earth taking a vacation or some such. He comes back to see his city and its 7,000,000 inhabitants gone and a smoldering crater in its place. He goes nuts and wacks a few of his fellow Lanterns to get their rings in a feeble attempt to bring the city back. He is ultimately banished by the Guardians.
Green Lantern III: Redemption
Hal manages to escape his banishment in order to sacrifice himself to save the galaxy.
Which JSA? The one from current continuity or the original with Superman, Batman, and Wonder Woman? Personally, I would choose the present day version.
1: Sins of the Father, beginning with David Knight’s (Edward Norton) first night on patrol as Starman, where a sniper kills him. The rest of the story is about hipster-bohemian-junk dealer Jack Knight (John Cusack) coming to terms with his family’s heroic legacy, and being forced to inherit the mantle of Starman from his father Ted (Paul Newman) and dead brother Jack, after Ted is captured by an old enemy, the Mist (Richard Harris). A former villain, the Shade (Jude Law) steps out of the shadows to help Jack save his father and protect Opal City. In the end, Jack makes peace with his father and has a conversation with his dead brother where they finally part as friends.
2: Sins of the Child, where the Mist’s daughter Nash (Angelina Jolie) duplicates her father’s experiment to give her his powers, and unleashes a brutal crime wave upon Opal City. Jack and Ted Knight and the Shade must rally their allies, including the O’Dares, a family of redheaded Irish cops (led by Sam Elliott as Matt O’Dare), and former Rat Pack entourage member and super-powered bank robber Jake “Bobo” Bennetti (Michael Madsen) against the new Mist and her goons, including the radioactive Doctor Phosphorous. During a quieter moment, Jack falls in love, but the Mist has a fiendish surprise in store for him, which he’ll find out in the final scene of the movie.
3: Grand Guignol, where Opal City is under siege, the Shade has been possessed, and villains old and new are preying on the innocent. Jack Knight and his allies, including Bobo Bennetti, Elongated Man (Ryan Stiles) and Phantom Lady (pin-up model Dita Von Teese) have to stop the Shade and whoever is pulling his strings, and Ted Knight, the original Starman, the foremost protector of Opal City, makes the ultimate sacrifice. The movie ends with Jack making a colossal decision that most superheroes never even get to consider.
SANDMAN 1: Combines elements of several of the graphic novels, but centers upon his capture in the English manor house with flashbacks to some of his prior adventures as depicted throughout the series and the modern storyline of his reawakening. Death is introduced of course (and given a spin-off movie line.)
SANDMAN 2: Thessaly- Gives more backstory (than is in the comic books) to his previous run-ins with the Thessalian, the other Endless and introduces the Corinthian as a villain (with flashbacks). Also has the Abandoning of Abbadon plotline (with Jude Law as Lucifer).
SANDMAN 3: Involves the death of the Sandman with a graphic masterpiece tavern and a series of flashbacks and the death plotline.