Thanks
This part is the ideal time to do sidequests since you have access to an airship and there is no mist or Iifa Tree roots blocking areas. It is also ideal to level your characters or preferred characters to roughly around lv.50 since things are going to get harder from there on. Any further and you won’t be able to come back until the start of disc 4 and you’d have annoying mist everywhere.
You can get Ultimate Weapons for Zidane, Dagger, Steiner, Freya and Quina by completing some of the sidequests and secrets. While you can do most of the sidequests later, its just better doing it at this time. :]