Since the catnip question has been answered I just tell how I went with dresspheres. Yuna started as songstress sometimes switching to white mage, Rikku as thief and Paine as warrior. Then I usually went with two good jobs and one rather "useless". I mastered every dressphere for everyone and that pretty much meant that there's nothing to go back to do in the game. Took me three playthroughs to get it all though. ^^