what would you do on those planets?
Tatooine would be appropriate as a starter planet.
Corsucant, or any other "city-planet", would be an ideal place for commerce. Not only the auction house, but perhaps gambling as well.
Kashyyyk and the ice planet should both be top-level adventuring planets, imo. They should be packed with dangerous creatures and maybe even mandatory PvP-flagging.
Of course you could put dungeons on any and all of these planets.