I think there's a discussion around here already regarding this... I'm not looking and linking it though.
Mustafar: The Works (CIS Droid Factory conquest)
Geonosis: Arena (Hero assault)
Utapau: Docking Platform (An expanded Utapau conquest map like they did with Kamino from SWBF1 to SWBF2 with multiple levels and tunnels into the rock)
Corruscant: City (A couple mod maps already tackle this idea)
Just a couple ideas... There's definitely plenty to work with still from the movies.. and unlimited IMO if you go into EU or even just the animated series offers a bunch of ideas.