Even MBFGW managed to take #1 for several days in its run.
If we're talking about films that never hit #1 even for a single day, I think Alvin & the Chipmunks remains the king there.
Both films are basically performing like the other doesn't exist. If there was any evidence that JW was causing a poor performance for IO, you may be onto something by saying that it "knocked IO around" but there's nothing that indicates that's been the case at any point in IO's run. If JW didn't exist, nobody would say that IO was disappointing in the slightest.
Similar, IO's release hasn't caused any change in the trajectory in JW. Both films are doing fantastically well, and have been since release.
I want him to do Avatar. That's where his passion is, after all.
I still want Battle Angel to happen, though. I'd like him to produce it and get someone else to direct.
The Empire Strikes Back vs. Shrek 2
Jurassic Park vs. Love Story
The Lord of the Rings: The Two Towers vs. Spider-Man
Mary Poppins vs. Thunderball
Star Wars vs. Home Alone
The Avengers vs. Grease
Raiders of the Lost Ark vs. Cleopatra
Ghostbusters vs. Beverly Hills Cop
The Lion King vs. Goldfinger
The Sting vs. Airport
Back to the Future vs. American Graffiti
Independence Day vs. The Robe
Fantasia vs. Pirates of the Caribbean: Dead Man's Chest
Jaws vs. Around the World in 80 Days
Forrest Gump vs. Star Wars: Episode I - The Phantom Menace
Jurassic World vs. Blazing Saddles
Butch Cassidy and the Sundance Kid vs. Batman (1989)
The Jungle Book vs. The Bells of St. Mary's
The Dark Knight vs. Ben-Hur
Titanic vs. Finding Nemo
Pinocchio vs. Snow White and the Seven Dwarfs
Spider-Man 2 vs. Animal House
101 Dalmatians vs. The Passion of the Christ
The Graduate vs. Star Wars: Episode III - Revenge of the Sith
The Lord of the Rings: The Return of the King vs. E.T.: The Extra-Terrestrial
Avatar vs. The Sound of Music
Return of the Jedi vs. The Dark Knight Rises
Whoever it is is going to be so strange to hear. Horner's score is really ingrained in that Avatar feeling. Nobody else really builds them the same way.
Still, James Newton Howard would be solid. Howard Shore could probably do it well, too. And I think Thomas Newman might be a solid choice.
Considering the original trilogy had that sense of being made for 8 year olds, that just makes RotS even worse.
Well, except for a guy's head getting crushed.
If we're looking at the percentage jump from a director's first to second movie, it's impressive. Whedon made a nice jump from Serenity to Avengers, too.
Gareth Edwards' jump from Monsters to Godzilla is pretty huge, too. And he could see another big jump with his next film.
I suppose it was technically The Lion King, which won two weekends in its original release (before getting supplanted by Forrest Gump), and then two more weekends on its 3D re-release.
However, in the way you're asking, it was Jurassic Park, of all things.