Michael Steele of course was not usually a beam of sunshine on stage, she had somewhat of a dark mysterious mystique, so Aimee Mann wouldn't be a huge departure. Annette Zilnskaus (sp??) in her appearances in the Bangles' small handful of shows since she rejoined the band, basically stays to the side and in the background.
Yes, the 1988 third (very underrated) album by 'Til Tuesday, Everything is Different Now has the title track, written by Jules Shear (who has some great indie acoustic folk stuff) as well.(Shear also wrote Mani Monday, I believe). Both Aimee and The Bangles know how to pick 'em. This song is pure pop confection.
Actually Aimee Mann might have been the most "logical" pick as a "replacement" for Michael Steele in the Bangles as a top bassist who could also sing occasional leads.
Actually Annette Zilinskas did. That's per recent podcast by Vicki+ Debbi and Susanna. In 2018, they offiically asked Annette to join the band again, before they made the 3 X 4 album.