I have a similar topic to this in General Sailor Moon; it's not exactly dreaming up actors for a live-action Sailor Moon so much as faces. Forgive me, but seeing as I selected actors before I'm going to reuse my choices.
Sailor Mars: Keiko Kitagawa
Yeah, she played Mars before and is the most successful actress to come from PGSM. Even though she did a great job in 2003-2004, her acting has improved phenomenally. She's always had the capability to ground the role and it's SCARY how appropriate she is just based on personality (Keiko is probably the most naturally-introverted idol Japan has seen in years). If a live action SM movie is ever made, I'm hoping they'll have a multi-racial cast. With this in mind, I'd prefer for the actress of Rei to be Japanese as Rei has dark hair, works at a shrine and has various other Japanese quirks.
Also, just look at her smile. She's tries so hard not to smile but can't stop herself. That is SOOO like Rei.
Sailor Uranus: Jana Knauerova
Okay. So she's not an actress. She's a model. But before then, she was a violinist. With her experience in the arts, it's fair to say she has the intellect and artistry to break into acting. But, let's be real: she
looks the part.
Sailor Pluto: Serinda Swan
Setsuna is very mysterious, has dazzling features and is the most adult/mature of the senshi. Serinda is a decent actress when she wants to be. Her complexion and features are perfect to me. She's so effortlessly sultry in a way that I imagine Setsuna to be.
I'll add more as they come to me.