I think Harley Quinn is their second most significant female character ('fourth member of the Trinity', my ass), and that's just kinda sad.
I feel like Black Canary, Hawkwoman and Vixen, in particular, and perhaps a few others, like Starfire, Raven and Big Barda, should have gotten far bigger pushes over the years. There never should have been, IMO, any argument over whether or not Martian Manhunter or Cyborg was the 'seventh' member of the big seven, when Wonder Woman was the only woman.
Vixen, IMO, is one of the most distinctive and dynamic 'non-Satellite era' Leaguers out there, and I'd really like to see more of her.