Haha, I'd actually make Asoka the central character!

She was annoying in the earlier seasons when the show was still finding its feet, but she is so much better since season 3 (especially with the costume change).

She would be the audience. We would get introduced to the universe, meet the characters, and develop and age as she does, much like Luke does in the OT.

I'd have no suggestion of Vader, no Yoda (like you suggested) and leave the trilogy at a point where ROTJ finishes (the Empire is not totally defeated, but the tide is turning).

Ventriss would be the main rival in the first film, with Dooku being the 'Emperor' character (mentioned, but not seen). I'd consider the second film to open with her betrayal, or possibly finish the film with that. Her return as a more sympathetic anti-hero could be the twist of the second film.

I'm hoping the series ultimately ends with Asoka quitting the order and fleeing. Ventriss will probably die, if they could be connected that would be superb.

We need to know about Padme, but she wouldn't be remotely important, and would already be Anakin's wife.