I believe the planets (to include other sites) to get into game first should be the ones from the KOTOR series. Would be great to see them again.
Dantooine
Kashyyyk
Manaan
Rakata Prime
A space station orbiting the Yavin system, or just Yavin IV
Telos (with the hidden academy)
Citadel Station
Malachor V
the jungle moon Dxun
Onderon
Would also like to see Dathomir and the witches!