Bah, Coruscant is too Clean...how about a real city like Nar Shaddaa? You have gangsters, scoundrels, and scum galore there. Much more fitting to the GTA setting.
Coruscant has a pretty shady underworld, and it would be BOSS to roll on up to the Senate Tower and start cappin' government officials.
But yeah, have a Nar Shaddaa expansion pack.