For the type of story and environments Lucas designed the film with, there really wasn't a whole lot more they could do in terms of building actual sets. Much of the film was constructed facade--the coruscant streets, the nightclub, padme's apartment, palpatine's office, the kamino landing platform, Jango Fett's apartment, Dex's diner, most of the jedi temple, some geonosis exteriors, the lars' garage, the geonosis arena, the geonosis hanger...thats really every single location in the film. And all the Naboo places were real locations. The only place where they could have (and should have) used actual location plates was the Geonosis clone war ground battle--even though its mostly constructed from photographs, they have been manipulated enough that it looks false; simply setting the battle on some kind of earth desert with a few hundred real extras would have been much more impressive. But thats my only complaint really.