Geonosis I doubt, since it's basically a rocky wasteland and we enough wasteland plantes already (Korriban, Tatooine, Hoth, ...). Yavin IV would be pretty cool.
Personally I'd like to revisit Manaan too. Koltoi is referenced several times in the game and it would make sense for both sides to fight over control of it. Dantooine runs a close second.
"When kolto was replaced in favor of bacta, the Republic abandoned Manaan, and the Selkath left Ahto City for their ancient cities in the depths of the planet's oceans. Manaan did not have further contact with the galaxy until the Selkath were enslaved by the Galactic Empire sometime during the Galactic Civil War."
"Bacta was invented by the Vratix on the planet Thyferra in antiquity, with the galaxy at large learning of its properties around 4,100 BBY."
4,100 BBY = Year 447 before the Treaty of Coruscant (BTC)
Sorry man, probably no Manaan :/