Definitely with you on the greatness of Help!.
Outside of the giant ruby-based comedy genre, I think Steely Dan should have made a gritty, French Connection-style '70s New York Cop drama. Skunk Baxter could have been their angry police chief, Cornelius Bumpus could have been Becker's informant and Michael McDonald would have been the drug kingpin they were out to bust. Chevy Chase would have played himself.
Similarly, instead of doing Darkness At the Edge of Town, the E-Street Band should have been cast for The Deer Hunter, with Springsteen in for DeNiro, Little Steven for Walken, Max Weinberg for John Savage and Clarence Clemons in for George Dzundza. The Vietnam parts would take place in Asbury Park instead, but the plot would still remain the same.