As long as groups like the Sea-Devils, the Blackhawks, and their ilk are returning in DC's stories, I cast my vote for The Mystery Analysts of Gotham.
During the "New Look Batman" era, they were five snoopy people who flitted in and out of Detective Comics, solving mysteries (hey, Batman is a busy guy, you know). Commissioner Gordon (the professional cop), Hugh Rankin (the private eye), D.A. Danton (um, the District Attorney), Art Saddows (the crime reporter), Martin Tellman (the armchair detective).
At the time, it was spoiled by having Batman in the stories, who overshadowed the Analysts. But make Jim Gordon their leader (giving him something to do other than limp) and the Mystery Analysts of Gotham would be a great back-up feature in Detective Comics. At least, better than "The Barker", "The Tailor", Josie Mac, or the Bald Guy in the Incomprehensible Storyline Better Left Forgotten ("the Jacobian"), which is what DC's been wasting its most prime comic book "real estate" on.