I've just started chapter 3. Yuna and Paine have mastered their defaut Dressphere's and Rikku's nearly mastered hers. I'm setting Yuna up to be an uber-mage with black and white mage. Paine is working on the trainer sphere, because it seems to be an excellent all-round class. Rikku steals a lot of nifty stuff with Master Thief and Sticky fingers, but I'm also working on the Alchemist sphere as well. I missed Dark Knight and I'm not up to the point where I can go back and get it, yet. I haven't really tried the Berserker and Lady Luck ones yet because I just got them. The only dressphere I don't use is Songstress, but I'm not that impressed with Gun Mage either.